CPP Presentation

2006 C++ Course Handouts January 2006

Notes: 1

3/4/2006 Jim Adams C++ Presentation -- Copyright 2004, 2005, 2006 1

C++ Programming and Computer Science

CIS162

CSC100

Version 17

2006

23/4/2006 Jim Adams C++ Presentation -- Copyright 2004, 2005, 2006

First Night RoadmapSocial AmenitiesAttendanceIntroductionsDiscuss SyllabusDiscuss Course ObjectivesMake Sure We Are Clear on AssignmentsWho Has Computer Access and C++ CompilersTalk a little About Computers and C++


Notes: 2


Subject Overview

C++ Programming.This course includes features to construct C++ programs and

functions. Topics discussed will be data types, functions, pointers, input/output routines, structures and disk access routines. Also discussed are inheritance, encapsulation, classes, members and overloading. Prerequisites: CIS152 or CIS155 or CIS156 or CIS157 or CIS158 or CIS102.

This is one of the most important and dynamic computer science subjects taught today. C++ language is used to develop operating systems, applications and programming tools. In fact, C++ is used to actually write other compilers such a C, Ada, COBOL and FORTRAN. This class will take a journey down the path of C++ programming. Additionally, we will discuss other popular related software and computer science topics. Upon completion of this course, you will have a crisp outlook and keen understanding of the computer language of choice in today’s world of computer science. Sound Exciting? Let’s go.


Course Objectives1. Explain the history of C++ and basic computer components2. Describe the software development process3. Use predefined data types to declare and manipulate variables and

arrays4. Use operators in arithmetic and Boolean expressions5. Design and develop structured/modular programs using various flow

control structures and functions6. Describe object-oriented concepts7. Design and develop programs using classes and object-oriented

programming techniques8. Process keyboard input and console output9. Debug simple and complex programming errors10. Use standard preprocessor commands11. Understand the concepts used in the construction of C++ programs,12. Understand and implement most C++ functions13. Understand basic structured programming concepts14. Understand encapsulation, inheritance, scope and overloading15. Improve your critical thinking skills16. Understand the relationship between high-level, low-level and

machine languages17. Understand bit-wise manipulation of data18. Understand data conversions from binary, decimal and hexidecimal


Notes: 3


An Excellent TextStarting out with C++,

Alternate Version4th Edition. Tony Gaddis, Judy Walters

and Godfrey Muganda

Supplemental Text Books

Problem Solving with C++. Savitch.C++ Programming: From Problem Analysis to

Program Design. Malik.Visual C++ .NET. Deitel.C++ Primer Plus. Stephen Prata.


Grading Policy

100% - 90% A89% - 80% B79% - 70% C69% - 60% DBelow 60 Ooops

Grading PolicyAssignments are presented with the intent of reinforcing the reading material and topics discussed in the classroom. Late assignments are welcome, but receive a 10 percent reduction for each week they are late. All external class assignments are expected to be typed.


Notes: 4


Student DeliverablesAssignment or Activity PercentHomework 32% (32 x 1 % each)

Midterm Exam 24 %Final Celebration 24 %Critical Thinking Paper 5 %Quiz-1 6 %Quiz-2 6 %Attendance 3 %

Total 100 %Extra Credit Papers 5 %

All sorts of ways to get an “A”


How To Calculate Your GradeAssignment or Activity Percent Actual ExtendedMidterm Exam 24% x 90% = .2160Homework 32% x 94% = .3008Critical Thinking Paper 5% x 95% = .0475Final Celebration 24% x 80% = .1920

Quiz-1 6% x 100% = .0600Quiz-2 6% x 60% = .0360Attendance 3% x 100% = .0300

Total .8823 Extra Credit Paper 5% x 90% = .0450

Grand Total .9273 (92.73%)

Example-1


Notes: 5


How To Calculate Your GradeAssignment or Activity Percent Actual ExtendedMidterm Exam 24% x 90% = .2160Homework 32% x 88% = .2816Critical Thinking Paper 5% x 95% = .0475Final Celebration 24% x 80% = .1920

Quiz-1 6% x 80% = .0480Quiz-2 6% x 60% = .0360Attendance 3% x 75% = .0225

Total .8436 Extra Credit Paper 5% x 90% = .0450

Grand Total .8886 (88.86%)

Example-2


Course Road MapClass-1 January 20In Class: Plan on covering the course syllabus, grading, homework

projects and some basic computer terminology. We will discuss where C++ is used, how memory is laid out as well as compilers and interpreters.

Reading: Read Chapter 1 and begin reading chapter 2 in the C++ text book by Tony Gaddis.

Deliverables: Review and familiarize yourself with this course and homework roadmap. Be thinking about a topic for your term paper.

Lab Work: None.Tests: None.

See Course Map Details, Pages MAP-1 through MAP-13

View Homework Projects

Online C++ Tutorial


Notes: 6


Course Road Map


College Calendar

SPRING SEMESTER - 2006Sat Jan 14 Classes Begin

Mon Jan 16 Observance of M L King BirthdayMon Feb 20 Observance of Presidents' Day

Fri Mar 3 Last Day for Withdrawal without Instructor's SignatureMon-Sun Mar 13-19 Spring Break

Mon Apr 24 Last Day Student Initiated Withdrawal AcceptedSun May 7 Last Day of Regular Classes

Mon-Thu May 8-11 **Final ExamsFri May 12 Commencement

Fri May 12 Spring Semester EndsMon May 29 Observance of Memorial Day


Notes: 7


Class StructureStructure of the Class

Discussions Each Class Night Roughly 2 hours per night of discussion /dialog

C++ and Software EngineeringSoftware Development and MethodologiesComputer TechnologyEncryption & Decryption TechniquesCareers in IT, BusinessEthics in the Computer Industry

Lab Work Roughly 1 hour per night32 Programming ExercisesHome or the School Labs

Class and Group ActivitiesC++ Expert Panel DiscussionsStudent Teach Back AssignmentsIn-Class Group Assignments


Grading Standards For C++ Programs

C++ Homework Standards for Each Program

Header Comments 5%

Other Comments 5%Screen Shot of Output 5%Indentation and Style 5%On time 10%C++ Code to achieve the result 70%


Notes: 8


Critical Thinking Term Paper

Critical Thinking Term PaperFive pages, double spaced, cover page, references.

Topics to Choose FromImplementing C++ functions and templatesorAll About C++ Classes and Structures


Grading Standards For Term Papers

Term PaperCover Page 5%

References 5%Grammar 5%Spelling 5%Length 5%Margins 5%Page Numbers, Dates, Headings 5%Content 65%


Notes: 9


Teaching Philosophy

I am here to teach, you're here to learnI believe if you apply yourself to the discussions and exercises you can learn this material, easily.I believe in respect for the studentI believe in respect for the technology


How We LearnWe will proceed through many different learning methods

LecturesDialogsDiscussionsPresentationsStudent Teach-BackGroup CollaborationWritingDebatesPractice by Doing C++ in ClassPractice by Doing C++ at HomeEmail ActivitiesResearching TopicsHave Some Fun, too


Notes: 10


Outcomes and AssessmentsStatement Regarding Outcomes and AssessmentThe faculty and programs at CGCC are dedicated to

effective teaching and successful learning with emphasis in the following areas: reading, speaking, listening, writing, mathematics, science, computer application skills, humanities, problem-solving, information literacy, critical thinking, and personal development.

Periodically, students will participate in formal and informal assessment activities that will help faculty improve programs and teaching strategies. These activities are designed to facilitate student growth in whatever combination of the above outcomes applies to a course.


Students with Disabilities

Statement Regarding Students with DisabilitiesStudents with disabilities are required to register for services in

the Disability Resources and Services (DRS) office in the Student Center at the beginning of the semester. Do not wait to visit the DRS office if you want support with any CGCC classes.

The DRS office will meet with you to determine accommodations based on appropriate documentation. This must be on file before any accommodation will be provided to students. You can contact the DRS office at (480)857-5188.

Faculty are not authorized to provide any accommodations nor can they approve any accommodations for students in this class


Notes: 11


Leaning Center

Information on Learning Center Services

The CGCC Learning Center's mission is to support students' academic learning by providing free tutoring and resources to reinforce and supplement classroom instruction and to assist CGCC students to achieve academic success. Free tutoring services are available for many CGCC courses. The Learning Center is located on the second floor of the Library, rooms L227, L228, and L229. The Center also provides instructional support resources in the form of videotapes, software, and print materials. For a schedule of tutoring hours, additional information or assistance contact the Learning Center at (480) 732-7231, or visit our website at: http://www.cgc.maricopa.edu/lc

Online C++ Tutorial


Plagiarism

Statement Concerning PlagiarismPlagiarism is defined as presenting the work of another as one's

own. More than four consecutive words from a source other than the writer constitute plagiarism when the source is not clearly identified in appropriate documentation format.

From the CGCC Student Handbook:"Plagiarism includes, but is not limited to, the use of paraphrase

or direct quotation, of the published or unpublished work of another person without full and clear acknowledgement. It also includes the unacknowledged use of materials prepared by another person or agency engaged in the selling of term papers or other academic materials."


Notes: 12


Instructor Contact Information

Jim Adams

Work: (480) 929-9803Email (Work): [email protected] (Home): [email protected] Page: www.softwaredynamix.com/javashop/index.php

Software Engineer 25+ yearsTeaching since 1996 (C++, Java, Statistics, VB, COBOL)Developed code using C, C++, FORTRAN, COBOL, Java, Assembler, VB, C#, PHP, PERLBS in Engineering, Mathematics MajorMBA Technology ManagementMS Systems and Software Engineering

Division Secretary: Carlene Weberg (480) 732-7043


Web Page

URL is:www.softwaredynamix.com/javashop/index.php

Contains lots of C++ related informationSyllabus and Course ObjectivesOnline Midterm and Final ExamsSample C++ Code Homework ProblemsContact InformationPrevious Test Scores


Notes: 13


Now, I Need Some Information..

On the 3x5 cards, write:

1. Name2. Phone3. Email Address4. Where You Work5. Hobbies or Interests


Syllabus Summary

Text BooksHomework & Lab TimeAttendanceClass StructureGradingC++ CompilersInstructor Contact InformationUpon completion of this course, you will have a crisp outlook and keen understanding of the computer language of choice in today’s world of computer science

Sound Exciting? Let’s Learn C++…


Notes: 14


Chapter 1

Introduction to C++, Computer Systems and Problem

SolvingComputer SystemsHardware, SoftwareCompilersGenerations of ComputersAlgorithmsSoftware Life CycleOrigins of C++Types of Programming ErrorsSample C++ ProgramsProblem Solving


Questions to Think About

What is Computer memory? How is it organized? What is it made of?What do we use it for?What types of things are stored there?What is a Program?


Notes: 15


Computer Systems

Input Devices

Scanners, ModemsMIDI DevicesZip Drives, Jazz Drives, Tape DrivesDisk DrivesKeyboard

Output Devices

CRTModemsMIDI DevicesZip Drives, Jazz Drives, Tape DrivesDisk DrivesPrinters

CPU

Main Memory

RAM

These are all things you can touch—hardware types of things. They send data to the CPU and they take information from the CPU. Hence the phrase, Input, Process, Output, or IPO.

Software is used to control these devices. C++ is the language of choice in managing and controlling hardware devices.


Computer Systems

Main Memory

Disk Secondary Storage

Input

Output

ALU

Bus

Primary Storage

CPUHardware Bus size determines C++ memory access size

Hardware

Registers


Notes: 16


Computer Memory Layout

E a c h b y t e h a s

00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D

Relative AddressBase Address,

say, 8000


Units of Measure

Binary 1 bit, either zero or oneBits Bunches of zeros & onesNibble 4 bits (1/2 byte)Bytes 8 bits (1 character)Words 16, 32 or 64 bits (Machine Dependent)Kilobytes KB 1024 bytesMegabytes MB 1 million bytesGigabytes GB 1 billion bytesTerabytes TB 1 trillion bytes

Milli, Micro, Nano, Pico .001, .000001, .000000001


Notes: 17


History of C and C++

Ken Thompson and Dennis Ritchie in 1972Started out on UNIXBCPL or B language (Used for O/S’s)They were looking for a clever way to build systems software without using AssemblerToday, C is on every platform, imaginableC, C++, Visual C++, Advanced C

Who knows the difference between system software and application software?

A high-level programming language developed by BjarneStroustrup at Bell Labs. C++ adds object-oriented features to its predecessor, C. C++ is one of the most popular programming language for graphical applications, such as those that run in Windows and Macintosh environments


Where Is C++ Used?

Sequential, Linear ApplicationsEvent Driven ApplicationsSystem software

Operating systems, DOS, sorts, utilitiesAnalogous to heart and lungs

ToolsCompilers, Data Utilities, (Copies, Sorts, Finds, etc)

RoboticsPick & Place, Industrial Robotics

Game SoftwareEmbedded Systems (Who can give an example?)Communication Software

Netscape, Internet Explorer, Modem-based Software, Printer Drivers, Communications Drivers

Application softwareAccounts Payable, Payroll, Inventory, Sales Analysis, Marketing, etc


Notes: 18


C++ is Powerful and Flexible

C++ has useful functions for implementing control systems and operating systems

Great for building stacks, queues, linked-lists

Fairly readable code

Excellent for reusable functions

Very PortableCan move source code from UNIX to PC to Mainframe very easily

If one stays within the confines of ANSI C

American National Standards Institute (ANSI)

Powerful and flexible


C++ is Programmer Oriented

Programmer orientedAccess to memory locationsBit manipulationsRobust set of operators (+, -, /, *, |, &&, etc)Character orientedNot very strict with respect to data types

Pascal is very strict, for exampleEasy to make mistakes, but, you can do most everything imaginableGood News: You can do anything with C++Bad News: You can do anything with C++


Notes: 19


Steps in Program Development

Questions to Think About1. What steps do you think we use to create a C++

program?2. Are there any formal methodologies?3. What are CASE tools?4. Can paper and pencil be of any value in this

computer programming world?5. What is Software Engineering?


Steps in Program Development

Define objectivesPreliminary design (Flow Chart Perhaps)

Write the code (Implies some kind of editor)

Compile & linkRun the programTest and debugMaintain and modifyDocument

Today, we tend to use an iterative approach

Process

Decision

InputOutput

O nlineStorage

Tape

Off-PageConnect

or

D isplay

ManualOpera tion

Predefined Process


Notes: 20


Flowcharting

Open File

Start

Read a Byte

EOF

Close File

Print Byte

Stop

Yes

No

Entity Relationship DiagramsState Transition Diagrams

Flow Charts


Developing a Solid Program

Break the program up into sections such as reading inputdisplaying outputprocessing of some kind

Design functions to be called that do specifically what is needed and to be very focused on what is to be done.

reading_input()display_headings()print_detail()accumulate_totals()calculate_mean()process_nc_data()attach_to_host()reverse_string()


Notes: 21


Systems Development Life Cycle

Preliminary Investigation

Systems Analysis

Systems Design

Systems Development

Implementation

Maintenance


Another Development Methodology

A. Conceptual Design Phase -- During the conceptual design phase, agency management identifies the need for a system, and develops a high level project plan.

B. Planning Phase -- During the planning phase, system developers and users determine functional, quality, and architecture requirements of the system identified in the conceptual design phase, design the system to meet those requirements, and plan for development and implementation.

C. Development Phase -- During the development phase, system developers code and test the system designed in the planning phase, and prepare for training and implementation.

D. Implementation Phase -- During the implementation phase, users learn and test the system to ensure it meets their requirements. If the users accept the system, systems developers install and convert to the new system.

E. Post Implementation/System Support Phase -- During the post implementation/system support phase, management, users, and systems developers continuously monitor the implemented system to ensure it measures up to the expectations and requirements developed in previous phases, and to enhance the system as needed to increase the system's useful life.


Notes: 22


Problem Solving Technique

Break Down the Problem into its component parts

InputProcessingOutput

Very popular in programming and technologySometimes it’s helpful to start with the Output

Screen layout, report layout, etc

Desk checkingManual testing with sample dataQuality assurance (QA)Walk through


Algorithms

Like a recipeSame as

DirectionsMethodsProcedures

An algorithm is a sequence of precise instructions that leads to a solutionWe’ll use the word “algorithm” a lot in this classSorting, searching, etcPayroll applications have many algorithms,

Bonus calculations, pay calculations, tax calculations


Notes: 23


Chapter 1 Summary

Introduction to Computer & Programming

Computer SystemsCompilersAlgorithmsSoftware Life CycleOrigins of C++Types of Programming ErrorsSample C++ Programs

Homework:1. Read Chapter 1 and 2 in the text

book2. Install C++ Compiler3. Type in some of the sample C++

programs in chapter 14. Start Critical Thinking Paper


Chapter 2

Introduction to C++

VariablesAssignment StatementsDeclarationscout#include directivesEscape SequencesData TypesArithmetic OperatorsSimple Flow ControlProgramming Style


Notes: 24


What is Binary?

Binary Numbering System00000001 100000010 200000011 300000100 400000101 500000110 600000111 700001000 800001001 900001010 1000001011 11

11111111 255

Look at the supplemental information in the last chapter of this handout..


Mechanics of Binary?

Mechanics of Number Systems

Decimal Number System123410=1x103+2x102+3x101+4x100

Binary Number System10012=1x23 + 0x22 + 0x21 + 1x20

Any number to the 0th power is 1Any number to the 1st power is the number

itself


Notes: 25


First Generation Programs--Binary

0100 1001490100 0101450011 1001390111 0010720011 11103E0000 0000001011 0011B31110 1111EF1010 1010AA0101 0101550000 11110F0001 11101E

0100 1001

4 9 in hex

01 001 001

1 1 1 in octal

each of which is 73

First there was actual binary. Then there was hex as a shorthand notation

Take 01001001 as an example


Second Generation Programs--Assembler

Address Inst Mnemonic0110 0100 00100100 org $1000110 0101 00100010 mov 0, r10110 0110 00011100 add 10, r10110 0111 00111001 sto r1, counter0110 1000 00011111 ret0110 1001 00000000 counter

end

We wanted an easier way to get to machine code from some type of human readable code.


Notes: 26


Third Generation—FORTRAN,COBOL, C, etc

INTEGER FACTORIALDO N=1,12WRITE (6,*) N,' factorial is

',FACTORIAL (N)END DOEND

OPTIONS /RECURSIVEINTEGER FUNCTION FACTORIAL (N)

!! The Factorial of an integer N is N * N-1 *

N-2 ... * 1. ! passing N-1 to perform the calculation.

Note that ! each recursive call to FACTORIAL will get

its own ! copy of N.!! If N is 1 or less, the result is 1. (We

assume thatIF (N .GT. 1) THENFACTORIAL = FACTORIAL(N-1) * N

ELSEFACTORIAL = 1

END IF

RETURNEND

PROCEDURE DIVISION.

Begin.

DISPLAY "Enter student details using template below".

DISPLAY "Enter -ID,Surname,Initials,CourseCode,Gender"

DISPLAY "SSSSSSSNNNNNNNNIICCCCG".

ACCEPT StudentDetails.

ACCEPT CurrentDate FROM DATE YYYYMMDD.

ACCEPT DayOfYear FROM DAY YYYYDDD.

ACCEPT CurrentTime FROM TIME.

DISPLAY "Name is ", Initials SPACE Surname.

DISPLAY "Date is " CurrentDay SPACE CurrentMonth SPACE CurrentYear.

DISPLAY "Today is day " YearDay " of the year".

DISPLAY "The time is " CurrentHour ":" CurrentMinute.

STOP RUN.


Fourth Generation ProgramsC++, Java, SQL, VB

#include <iostream>using namespace std;

main(){

cout << “This is a simple C++ Program “ << endl;

}


Notes: 27


Sample C++ Program


void main(){

int length, width, area;cout << "Calculate the area of a rectangle \n\n";cout << "Enter Length:";cin >> length;cout << "Enter width:";cin >> width;

area = length * width;

cout << "Area of the rectangle is " << area;cout << "\n\n";

}


Basic C++ Construction


int main(){variable declarations

C++ statements

return(0);}

Include directive

Main Body

Return statement


Notes: 28


Use of Semicolons

All C++ statements, except function definitions, end with a semicolon ;

int x = 100;cost = 100.99;cout << “This is C++ at its finest \n”;display_text(x);return(0);printf(“C++ is Very Cool..”);


Code Blocks & White Space

Code BlocksBraces

{Marks the begin and end of a block of code

}

White Space


Notes: 29


Code Blocks & White Space

C++ code fragment shown earlier can be written like this:#include <iostream>using namespace std;void main () {

cout << "This is a simple C++ Program";cout << "\n"; }

Can also be written like this:#include <iostream>using namespace std;void main ()

{

cout << "This is a simple C++ Program";cout << "\n";

}


Syntax v. Semantic Errors

Syntax or Compile Time errors are caused by uncertain coding that the compiler cannot understand. Sometimes called Semanticerrors.

cout << “Test Text;

Run Time errors cause a program to stop or halt abruptly.z = 0;x = y / z;

Logic errors cause some erroneous action to be takenint x=10;cout << “X cubed is:“ << x*x;

if (sales_amount > 1.00) then sales_tax = 0


Notes: 30


As you might guess,Compilers are extremely complex pieces of softwareCompilers must parse each line of source code

Called a translation unitdetect syntax errorsgenerate variable space in the symbol tablegenerate assembler code equivalent to the C codeassemble the assembler code into object codelinks object code into an executable file .EXE

Compilers


Source, Object and Executable

C++ is the Source CodeCompiler converts to an Object moduleThe Linker converts the object module to an Executable

C++ Source Compile Object Linker .EXE

User types in C++ Source Code


Notes: 31


Compile and Build Process1. Look at the Problem you need to solve2. Design with paper and pencil the input, process and

output3. Open the IDE (MS or Borland for example)4. Type in your C++ code5. Compile it (F7 on MS)6. Fix Errors7. Run the Program

Compiler creates several files1. C++ Source (You type this in)2. .exe file3. .dsp files4. .ncb files5. .prj files6. .opt files 7. .plg files


How to Print Results

1. Click the upper left corner2. Choose “Edit” then “Mark”3. Select the text you want to print4. Click the upper left corner, again5. Select “Edit” and then “Copy”6. Copy and paste to MS Word or

back into the compiled source code

1. Click the upper left corner2. Choose “Edit” then “Mark”3. Select the text you want to print4. Click the upper left corner, again5. Select “Edit” and then “Copy”6. Copy and paste to MS Word or back into the compiled source code


Notes: 32


Questions1. Who can discuss the difference

between a keyword and a variable?2. What is a C++ Comment?

C++ Keywords and Variables


1. asm2. auto3. break4. bool5. case6. catch7. char8. class9. const10. continue11. default12. delete13. do14. double15. else16. enum17. extern18. explicit19. false20. float

21. for 22. friend23. goto24. if25. inline26. int27. long28. mutable29. namespace30. new31. operator32. private33. protected34. public35. register36. return37. short38. signed39. sizeof40. static

C++ Keywords41.struct42.switch43.template44.this45.throw46.true47.try48.typedef49.typeid50.typename51.union52.unsigned53.using54.virtual55.void56.volatile57.while


Notes: 33


Tokens

Smallest source-code element recognized by the compiler

keywordsidentifiersconstantsstringsoperatorspunctuator

int counter=0; counter++;


Special Characters in C++

Char Name Description// double slash beginning of comment# pound sign preprocessor directives< > less than/greater set wrap file names in include statements<< double less than used on cout object>> double greater than used on cin object( ) parenthesis used in functions for passing arguments[ ] brackets used for array subscript notation{ } braces marks beginning and end of code block“ “ quotes used to designate a quoted string; semicolon C++ statement termination character


Notes: 34


Five Type of Statements in C++

Null Statements (Comments)

Declaration StatementsAssignment StatementsControl StatementsFunctions


Comments in C++// C++ Comments// Continue until the end of line

x = 100; // comments can go here

// ;-------------------------------------// ; Comments about a section of code// ;-------------------------------------x = q;y= x / 12.2 * (x * 1.223);/* standard C comment text */

x = 700; /* comments can go here */

/* ;-------------------------------------; Comments about a section of code;------------------------------------- */

x = q;Y = x / 12.2 * (x * 1.223);


Notes: 35


Comments in any program/* ;----------------------------------------------------------;

; Program Name: Problem 3.21 ;; File: HW3_21.cpp ;; Description: Brief description of what ;; the program does ;; Author: Jim Adams ;; Environment: MS C++ 6.00 ;;----------------------------------------------------------; */

Or// ;----------------------------------------------------------;// ; Program Name: Problem 3.21 ;// ; File: HW3_21.cpp ;// ; Description: Brief description of what ;// ; the program does ;// ; Author: Jim Adams ;// ; Environment: DEV C++ 4.9 ;// ;----------------------------------------------------------;


What Is a Variable

A Variable is place in computer memory where we store information used in our programs.

For example, say we have a program where we prompt the user for name, address, city state and zip.

We use Variables to store this information for later use.

The contents of a variable are just that—variable.

Your computer's memory can be viewed as a series of cubbyholes. Each cubbyhole is one of many, many such holes all lined up. Each cubbyhole or memory location is numbered sequentially. These numbers are known as memory addresses. A variable reserves one or more cubbyholes in which you may store a value.


Notes: 36


What Is a VariableA Variable is place in computer memory where we store information used in our programs.

Each data variable has three componentsIts Name,

Its Value,

Its Type


Variable DeclarationAll variables must be declared before they are used

SyntaxType_Name Variable_Name_1, Variable_Name_2, Variable_Name_n;Type_Name Variable_Name=initial_value;Type_Name Variable_Name(initial value);

Examplesint result,

count, age, length,myVariable;

int accum=0;int counter(0);char StatusByte;float cost_of_goods_sold;double national_debt=0.0;bool complete;


Notes: 37


Variable Declaration

Variable Name Choiceup to 31 characters (ANSI Standard)lowercase & uppercaseunderscore charactervariables must begin with a letter or the underscore character

Microsoft allows 247 characters



Each variable takes a certain amount of memory space depending on the type of compiler

int count; // 2 bytes internallyint i;

char ch=‘A’; // 1 byte internallychar status;

float cost; // 4 bytes internallyfloat vector;

double nations_debt; // 8 bytes internallydouble sum;


Notes: 38



Names you supply for variable types of informationWe Declare Variables More Examples:

int result;int count;

Variables (identifiers) are case sensitiveint Adder;int adder; // these are different


Meaningful Variable Names

Use Meaningful Names

x = y * z;

distance = speed * time;tax = cost * tax_rate;Voltage = Amperes * Resistance;


Notes: 39


Meaningful Variable NamesDeclaring a VariableStay clear of variables with names like: J23qrsnf, xyz, Mary. Good variable names tell you what the variables are for; using good

names makes it easier to understand the flow of your program. The following statement defines an integer variable called myAge:

int myAge; // called Camel Case

As a general programming practice, avoid such horrific names as J23qrsnf, and restrict single-letter variable names (such as x or i) to variables that are used only very briefly. Try to use expressive names such as myAge or howMany. Such names are easier to understand three weeks later when you are scratching your head trying to figure out what you meant when you wrote that line of code.


Valid Variable Declarations

Valid Variable Namesdepositend_balwithdrawalcontinue_processResultFieldResultAnnualSalaryCostOfGoodsSoldSelling_Pricequantity_on_hand


Notes: 40


Invalid Variable Declarations

Invalid Variable Names2002DepositAmountend balwithdrawal.amtcontinuecharcoutintResult-Field1selling_price$cost


Data Types

Character Data Typeschar stores a single characterstring stores a series of characters

Integral Data Typeslong stores large integersint -3, -2, -1, 0, 1, 2, 3, 4, 5, etcshort

Fractional Data Typesfloat numbers like 3.14159double numbers like 3.141598658934569876542301

Logical Data Typesbool true or false


Notes: 41


Data Types

Type Specifiers

int 16 bitslong 32 bitsshort 8 bitschar 8 bitsfloat 32 bitsdouble 64 bitsbool 8 bitsstring N/A

Type Modifiers

unsignedsigned


Variable Data TypesType Size Valuesint 2 bytes -32,768 to 32,767unsigned int 2 bytes 0 to 65,535unsigned short int 1 byte 0 to 255short int 1 byte -127 to 127unsigned long int 4 bytes 0 to 4,294,967,295long int 4 bytes -2,147,483,648 to 2,147,483,647char 1 byte 256 character valuesfloat 4 bytes -3.4e-38 to +3,4e38double 8 bytes -1.7e-308 to +1.7e308bool 1 byte true or false

Note: The sizes of variables might be different from those shown in above, depending on the compiler and the computer you are using. If your computer had the same output as was presented above, then this should apply to your compiler. If your output was different, you should consult your compiler's manual for the values that your variable types can hold.


Notes: 42


Integer Data Typesshort 0111 1111unsigned short 1111 1111int 0111 1111 1111 1111 unsigned int 1111 1111 1111 1111long 0111 1111 1111 1111 1111 1111 1111 1111unsigned long 1111 1111 1111 1111 1111 1111 1111 1111

Signed means you can have both positive and negative values. The high-order bit, the sign bit, is used to denote negativity.Unsigned means you can store only positive values. The sign bit is used for data not a sign.

Sign Bit


Size of an IntegerSize of IntegersOn any one computer, each variable type takes up a single unchanging amount of room. That is, an integer might be two bytes on one machine, and four on another, but on either computer it is always the same, day in and day out.

A char variable (used to hold characters) is most often one byte long. A short integer is two bytes on most computers, a long integer is usually four bytes, and an integer (without the keyword short or long) can be two or four bytes.

A character is a single letter, number or symbol that takes up one byte of memory.


Notes: 43


Integer Use Example#include <iostream>using namespace std;

void main(){

int checking;unsigned int miles_driven;long days;

checking = -2500;miles_driven = 4276;days = 186650;

cout << “Checking balance " << checking << " dollars" << endl;cout << "We drove " << miles_driven << “ miles” << endl;cout << "We flew " << days << " days to get to Saturn\n\n\n";

}

Our checking balance is -2500 dollarsWe drove 4276 milesWe flew 186650 days to get to Saturn


Overflow and UnderflowWhat happens when a numeric variable reaches maximum /

minimum values for a given data type

Integer with 32767 and 1 is added gives -32768because the sign bit is set and all other bits are zero

Underflow is a maximum negative number going positive, so, -32768 minus 1 = +32767

0111 1111 1111 1111

+ 0000 0000 0000 0001

1000 0000 0000 0000


Notes: 44


Break


char and string Data Typeschar 0000 0000 through 1111 1111string Any number of bytes

On some systems a character data variable is two bytes.Holds values like ‘A’, ‘B’, ‘$’

char ch;char status_byte=‘ ‘;string first_name=“Santa”;string last_name=“Claus”;string movie_title=“The Good, The Bad, The Ugly.”;


Notes: 45


Using Character Variables#include <iostream>using namespace std;

void main(void){

char letter;

letter=65;cout << letter << endl;letter=66;cout << letter << endl;letter=90;cout << letter << endl << endl;

letter='A';cout << letter << endl;letter='B';cout << letter << endl;letter='Z';cout << letter << endl;

}

Generated OutputABZ

ABZ

Code Verified 03/19/2003

A = 01000001

B = 01000010


String Variable Declaration

String Data Typestring myName;string yourName;string bookTitle;string Inventory_Item_Description;

Same aschar myName[30];char yourName[30];char bookTitle[45];char Inventory_Item_Description[60];

An Array of Characters


Notes: 46


Using String Variables#include <iostream>#include <string>using namespace std;

void main(){

string myName;string yourName;string bothNames;

myName =“Ada Lovelace";yourName ="Sally Ride";bothNames =myName;bothNames.append(yourName); // More on this later

cout << myName << endl;cout << yourName << endl;cout << bothNames << endl;

}

Generated OutputAda LovelaceSally RideAda LovelaceSally Ride



Floating Point Data Typesfloat 4 bytesdouble 8 byteslong double 8 bytes. Some use 10 or 16 bytes

IEEE 754-1985 governs binary floating-point arithmetic. It specifies number formats, basic operations, conversions, and exceptional conditions. The related standard IEEE 854-1987generalizes 754 to cover decimal arithmetic as well as binary.bits 0-22 are fraction (mantissa)bits 23-30 are the exponentbit 31 is the sign bit

http://www.nuvisionmiami.com/books/asm/workbook/floating_tut.htm


Notes: 47


Floating Point Data Types

float 4 bytesdouble 8 byteslong double 8 bytes. Some use 10 or 16 bytes

float Range is -1.2e-38 to 3.4e38double Range is -2.2e-308 to 1.8e308


Boolean Variable Declaration

Boolean Data Typebool a_switch;bool status_byte=true;bool We_Are_Finished=false;bool We_Have_Data;bool x;

Generally used to make C++ programs more readable.

do{

c++ statements}while (We_Have_Data);


Notes: 48


Boolean Variable Declaration#include <iostream>using namespace std;

void main(){

bool are_we_finished;

are_we_finished = false;cout << are_we_finished << "\n\n";

are_we_finished = true;cout << are_we_finished << "\n\n";

}

Generated Output

0

1


Type Specifier Examples

int x;unsigned int y;signed int distance;float cost;short int counter;long big_counter;unsigned long HugeCounter;double mass_of_sun;char ch;


Notes: 49


Equivalents

Type Specifier Same Assigned int int or signedunsigned int unsignedsigned char charunsigned char no equivalentshort int short or signed shortsigned long int long or signed long


Simple Arrays

char name[5] = “TEST “;char address[25]=“”;char response[4]=“YES”;char myArr[20];char buffer[1000];int arr[100];float costs[1000];


Notes: 50


Internal Data Representation

Say, we have the following variable declarations

int x = 100;char ch = ‘A’;char name[4] = “TEST“;short int counter = 1;


Internally, Looks Like This . . . .

100 A T E S T 1

00000000 01100100 01000001 01010100 01000101 01010011 01010100 00000001---- 2 bytes ------ -1 byte- ---------------- 4 bytes ------------------ 1 byte

See Appendix-A, page 1121 in the text for all ASCII Characters


Notes: 51


ASCII v. Numeric


Assignment Statements

We assign values to the declared variables

Syntax:Variable = Expression

Simple Examples:x = 1;a = x * 100;b = 0;ch = ‘A’;z = (d/2) + 40;cost = 154.90;mass = 300000;Distance_to_Moon = 210000;counter = counter + 1;


Notes: 52



Variable Initialization is Important in C++

Simple Examples:int x = 1;int count = 0;char ch = ' '; float cost = 0.0;double mass(0.0);

int main(){

x = 1;count = 0;mass = 0.0;cost = 0.0;ch = ' ';

}

Initialized at compile time

Initialized at run time



Multiple AssignmentsAn unusual feature of C++ is the fact that an

assignment statement also has a value. The value of the assignment statement can itself be assigned to another variable. For example, the statement a = 77 has a value of 77. So we can have

b = a = 77; // both variables take the value 77


Notes: 53


The Beginning of Every C++ Program


Or

#include <iostream.h>


The cout Object

cout (character out)

Syntaxcout << variable-1 << variable-2 << text-1 << text-2;

Examplesint input_number=1000;cout << “Enter a number less than 100”;cout << “Number entered is ” << input_number << endl;cout << “Press Enter \n”;


Notes: 54


The cout Object

Examplescout << “This is a test”;

cout << “This “<< “is “<< “a “<< “test “;

cout << “This is a test \n\n\n”;cout << “This is a test” << endl << endl << endl;


The endl Object

endl stands for “End of Line”Pronounced “end-ell”

We also use the “backslash n” to accomplish the same effect

cout << “\n”;cout << endl;


Notes: 55


More Detailed Escape Sequences


#define -- preprocessor command

#define

preprocessor commandused for defining constants

Examples:#define PI 3.14159#define GRAVITY 32.2#define LF 10#define CR 13


Notes: 56


#define -- preprocessor command#include <iostream>using namespace std;#define PI 3.14159#define MAX 5

float diameter=10.5;float circumference=0.0;

void main(void){

circumference = diameter * PI;cout << "Circumference is " << circumference << endl;cout << "Where Pi is "

<< PI << " and diameter is " << diameter << endl;

cout << MAX;}

Generated OutputCircumference is 32.9867Where Pi is 3.14159 and diameter is 10.5


#define -- preprocessor command#include <iostream>using namespace std;#define begin {#define end }#define display cout <<#define read_screen cin >>#define program int main(void)

int age;

programbegin

display "Enter your age:";read_screen age;

end

Can actually define your own language


Notes: 57


#define -- preprocessor command

#include <iostream.h> Standard C++ #include <ctype.h> Character Handling#include <math.h> Math and Trig Functions#include <stdlib.h> General Utilities#include <stdio.h> Basic Input & Output#include <errno.h> Error Handling#include <fstream.h> C++ File I/O#include <string.h> String Handling#include <time.h> Date and Time Structures#include <signal.h> Signal Handling


Chapter 2 Summary

Introduction to C++

VariablesAssignment StatementDeclarationscoutEscape SequencesFormatting NumbersData TypesVarious OperatorsProgramming Style


Notes: 58


Chapter 3

C++ Console Interaction

CinI/O ManipulatorsPrinting Hex and OctalOperatorsExpressions


cin Object

cin (character in)

Syntaxcin >> variable-1 >> variable-2 >>. . . ;

Examplescin >> number1;cin >> mass_of_sun >> distance_from_earth;


Notes: 59


cin Object#include <iostream>using namespace std;

void main(){

int whole;float fraction;char letter;

cout << "Enter an integer, a float and a character:";cin >> whole >> fraction >> letter;

cout << " Whole Number is:" << whole << endl;cout << "Fractional Number is:" << fraction << endl;cout << " Letter Entered is:" << letter << endl;

} // end of main

Enter an integer, a float and a character: 1234 1234.456 B

Whole Number is:1234Fractional Number is:1234.46

Letter Entered is: B


Inputting a String (using char)// Also known as C-Strings#include <iostream>#include <string>using namespace std;

void main(){

char fullname[50];

cout << "Enter your full name: ";cin.getline(fullname, 50);

cout << fullname << endl;}

Enter your full name: Samuel F. B. MorseSamuel F. B. Morse

Member Function

cout and cinare Objects


Notes: 60


Inputting a String (using string)

#include <iostream>#include <string>using namespace std;

void main(){

string st;

cout << "Enter your full name:";getline(cin, st);

cout << st << endl;}

Enter your full name: Samuel F. B. Morse

Samuel F. B. Morse

cin object


Stream I/O Library Header Files

Note: There is no “.h” on standard header files.Be careful about “using namespace std”

iostream -- contains basic information required for all stream I/O operationsiomanip -- contains information useful for performing formatted I/O with parameterized stream manipulatorsfstream -- contains information for performing file I/O operationsstrstream -- contains information for performing in-memory I/O operations (i.e., into or from strings in memory)


Notes: 61


I/O Manipulatorscout.setf(ios::fixed);cout.setf(ios::showpoint);cout.precision(4);

Sets the precision and attributes to be used on subsequent cout and other I/O functions

setf attributesios::fixed // don’t use scientific notationios::scientific // use scientific notationios::showpoint // always show a decimal pointios::noshowpoint // do not show a decimal pointios::showpos // show a plus on positiveios::noshowpos // show a plus on positiveios::right // right justifyios::left // left justify


Classes for Stream I/O in C++

ios is the base class.istream and ostream inherited from iosifstream inherits from istream (and ios)ofstream inherits from ostream (and ios)iostream inherits from istream and ostream (& ios)fstream inherits from ifstream, iostream, and ofstream


Notes: 62


C++ Stream I/O -- Stream Manipulators

C++ provides various stream manipulators that perform formatting tasks.Stream manipulators are defined in <iomanip>These manipulators provide capabilities for

setting field widths,setting precision,setting and unsetting format flags,flushing streams,inserting a "newline" and flushing output stream,skipping whitespace in input stream


I/O Manipulator SummaryThere are several other manipulators that can be inserted into an output stream (on many systems you will have to use #include <iomanip.h> to use these)

dec Use decimal base oct Use octal base hex Use hex base endl End of line ends End of string ('\0') right force right justificationleft force left justificationfixed Fixed pointshowpoint Show the decimal pointflush Flush output buffer setw(w) Set output width to w (0 is default) setfill(c) Set fill character to c (blank is default) setprecision(p) Set float precision to pBoolalpha Use strings true and falsenoboolalpha Use numeric 0 and 1 for booleanuppercasenouppercaseskipws Skip white space on inputnoskipws Don’t skip white space on input


Notes: 63


I/O Manipulator Example#include <iostream>using namespace std;

void main () {cout.setf ( ios_base::hex, ios_base::basefield ); // set hex as the basefieldcout.setf ( ios_base::showbase ); // activate showbasecout << 700 << endl;cout << 255 << endl;

cout.unsetf ( ios_base::hex ); // deactivate hexcout.setf ( ios_base::oct ); // activate octalcout << 700 << endl;cout << 255 << endl;

cout.unsetf ( ios_base::oct ); // deactivate hexcout.unsetf ( ios_base::showbase ); // deactivate showbasecout << 700 << endl;cout << 255 << endl;

}

Output0x2bc0xff

012740377

700255

Code tested 10/28/2002


setprecision() Example#include <iostream>#include <iomanip>using namespace std;

void main(){

double cost=1234.1234;

cout << fixed << setprecision(6) << cost << endl;cout << fixed << setprecision(5) << cost << endl;cout << fixed << setprecision(4) << cost << endl;cout << fixed << setprecision(3) << cost << endl;cout << fixed << setprecision(2) << cost << endl;cout << fixed << setprecision(1) << cost << endl;cout << fixed << setprecision(0) << cost << endl;

}

1234.1234001234.123401234.12341234.1231234.121234.11234


Notes: 64


I/O Manipulator setw() Example

#include <iostream>#include <iomanip>using namespace std;

void main(){

double cost=1.12;

cout << fixed << setprecision(2);cout << setw(9) << cost << endl;cout << setw(8) << cost << endl;cout << setw(7) << cost << endl;cout << setw(6) << cost << endl;cout << setw(5) << cost << endl;cout << setw(4) << cost << endl;cout << setw(3) << cost << endl;

}

1.121.121.12

1.121.12

1.121.12


Using the IO Manipulators#include <iostream>#include <iomanip>using namespace std;

void main () {cout << setfill('0');cout << setw(5) << 700 << endl;cout << setw(5) << 255 << endl;

// print the numbers in hexidecimal formatcout << setw(5) << hex << 700 << endl;cout << setw(5) << hex << 255 << endl;

// print the numbers in octal formatcout << setw(5) << oct << 700 << endl;cout << setw(5) << oct << 255 << endl;

}

Output0070000255002bc000ff0127400377



Notes: 65


Printing HEX & Octal


// Start of main logic sectionvoid main(void){int num=192;cout << "[" << setw (6) << setfill('*') << num << "]" << endl; cout << hex << "[" << setw (6) << setfill('*') << num << "]" << endl; cout << oct << "[" << setw (6) << setfill('*') << num << "]" << endl; cout << dec << "[" << setw (6) << setfill('*') << num << "]" << endl; cout << setprecision(4) << 3.14159 << endl; cout << flush;}

[***192]

[****c0]

[***300]

[***192]

3.1416

Output

Validated 7/13/2001


Let’s See What We Know!#include <iostream>#include <iomanip>using namespace std;

void main(){

double x;double y;double value;

// Get The User Inputcout << "Enter a number:";cin >> x;cout << "Enter another number:";cin >> y;value = (x * y) + x;

// Output Section Onecout << "Values Entered: "

<< fixed << setprecision(4) << setw(11)<< x << setw(11)<< y << endl;

cout << "Final Value: " << value << endl;}

Enter a number:123.33Enter another number:432.44Values Entered: 123.3300 432.4400Final Value: 53456.1552

Generated Output



Notes: 66


sizeof() Operatorsizeof() operator

Used to obtain the size of any particular data typeExamples:


void main(){

int s;char ch;float cost_of_goods;double mass_of_the_earth;long distance;

s = sizeof(float);cout << "Size of an Integer is: “ << sizeof(int) << endl;cout << " Size of a Long is: “ << sizeof(distance) << endl;cout << " Size of a Short is: “ << sizeof(short) << endl;cout << " Size of a Float is: “ << sizeof(cost_of_goods)<< endl;cout << " Size of a Double is: “ << sizeof(double) << endl;cout << " Size of a char is: “ << sizeof(char) << endl;

}

Size of an Integer is: 2Size of a Long is: 4

Size of a Short is: 1Size of a Float is: 4

Size of a Double is: 8Size of a char is: 1


Operator Precedence

( ) Parentheses- + ++ -- Unary Operators* / % Multiply, Divide, Modulo+ - Plus, Minus< > <= >= Greater-Than, Less-Than== != Equal to, Not Equal to&& And|| Or= Set


Notes: 67


Operators & Precedence

Plus, Minus, Multiply, Dividex = 100; /* set x to 100 */x = x + 10; /* set x to 110 */y = x / 2; /* set y to 55 */z = y * 10; /* set z to 550 */w = z - 50; /* set w to 500 */a = ((x + 10) / 2 * 10) - 50;

A word of Cautionbutter = 25.0 + 60.0 * n / scale;


Mathematical Expressions

Y = 3X2

Y = (3 * X) / 2;Y = (X / 2) * 3;Y = (3 / 2) * X;


Notes: 68


Exponents in C++

y = 9x3+25y = (9 * pow(x,3)) + 25;

y = (9x3)5

y = pow((9 * pow(x,3)),5);

Exponent Functiony=pow(n, q); // n raised to the power of q


Some Math Functions in C++

abs y=abs(x); Absolute value

cos y=cos(x); Cosine

log y=log(x); Natural log

log10 y=log10(x); Log base 10

sin y=sin(x); Sine in radians

sqrt y=sqrt(x); Square root

tan y=tan(x); Tangent

pow y=pow(n, q); n to the power of q


Notes: 69


Sine Function in C++

#include <iostream>#include <cmath>using namespace std;#define PI 3.14159

void main(){

double y, x;// 57.3248 degrees per radiany=sin(PI/2); // 90 degreescout << y << endl;y=sin(PI/4); // 45 degreescout << y << endl;y=sin(PI/2); // 90 degreescout << y << endl;y=sin(PI/3); // ?cout << y << endl;y=sin(0.5244); // 30 degreescout << y << endl;

}

10.70710610.8660250.500694

All trig functions in C++ assume radian measure


strlen() Function

strlen() operatorUsed to obtain the size of a string’s contents


void main(){

int len;char myName[30];

strcpy(myName, "Santa Claus");len=strlen(myName);cout << myName << endl;cout << " Content Length:" << len << endl;cout << "String Capacity:" << sizeof(myName) << endl;

}

Santa ClausContent Length:11

String Capacity:30


Notes: 70


Symbolic Constants

Used to guarantee integrity of a variable READ ONLY VariableCalled A Symbolic Constant

float x = 100.00;const float PI = 3.14159;const float SQUARE_ROOT_OF_2 = 1.4142;

int main(void){

x = 3 / SQUARE_ROOT_OF_2; // OkayPI = 3.2; // Not gonna happen

}


Literal Constants

Floating PointIntegerCharacter

A number, character or string that can be used as a value in a program.


Notes: 71


Floating Point Constants

15.75 // 15.751.575E1 // 15.751575E-2 // 15.75-2.5e-3 // -0.002525e-4 // 0.0025

All floating point constants are stored as double precision unless otherwise stated.

110.21F floating point110.21D double


Integer Constants

10L Long Constant79L Long Integer Constant776745UL Long Unsigned778866LU Long Unsigned12345 Typical Integer Constant


Notes: 72


Numeric ConstantsInteger constants can be decimal, octal or hexidecimal.

(base 10, 8 & 16)// Decimal Constants (Base 10)1013232179

// Octal Constants (Base 8)0120204076663

// Hexidecimal Constants (Base 16) Hex for short0xa or 0XA0x840x7db3


Character ConstantsUsed for letters of the alphabet, special characters, etc.Wrapped in single quotes: ‘a’ ‘B’Can be escape characters: ‘\n’ ‘\a’Can be hex or octal escape sequence: ‘\x07’

Examples:char ch = 'Q';char_code = '$';

char ch2 = 't';char ch3 = 116; // 116 is little t

char ch4 = '0x74'; // hex 74 is little t

ch = ‘t’;ch = 116;


Notes: 73


Operators= Assignment < less than<= less than or equal== equal to> greater than>= greater than or equal!= NOT equal to~ Compliment| Boolean Or& Boolean And ^ Exclusive Or>> Shift right<< Shift Left&& Logical And|| Logical Or! Not Operator

++ Auto Increment-- Auto Decrement+= Increment-= Subtract*= Multiply/= Divide%= Modulo% Modulo+ Add- Subtract* Multiply/ Division. Dot Operator:: Scope Resolution


Incrementing A VariableThe most common value to add (or subtract) and then

reassign into a variable is 1. In C++, increasing a value by 1 is called incrementing, and decreasing by 1 is called decrementing. There are special operators to perform these actions

Say we have,int x=0;

Incrementx=x+1; // Traditionalx+=1; // shorthand for x=x+1x++; // postfix mode, same as x=x+1++x; // prefix mode, same as x=x+1


Notes: 74


Decrementing a VariableThe most common value to add (or subtract) and then

reassign into a variable is 1. In C++, increasing a value by 1 is called incrementing, and decreasing by 1 is called decrementing. There are special operators to perform these actions

Say we have,int x=10;

Decrementx=x-1; // Traditionalx-=1; // shorthand for x=x-1x--; // postfix mode, same as x=x-1--x; // prefix mode, same as x=x-1


Incrementing and Decrementing

Say we have,int x = 10;

Incrementx=x+5; // Traditionalx+=5; // shorthand for x=x+5

Decrementx=x-5; // Traditionalx-=5; // shorthand for x=x-5


Notes: 75


Postfix / Prefix Example#include <iostream>using namespace std;int number=2;int result=0;main(){

result = 2*(number++);cout << "Result using postfix notation:" << result

<< " " << number << endl << endl;

number=2;result = 2*(++number);cout << "Result using prefix notation: " << result

<< " " << number << endl;}


Result using postfix notation:4 3

Result using prefix notation: 6 3


Short-cut Assignment Operators

scores += 20; same as scores = scores + 20;dimes -= 2; same as dimes = dimes - 2;cars *= 4; same as cars = cars * 4;time /= 2.90;same as time = time / 2.90;reduce %= 3; same as reduce = reduce % 3;


Notes: 76


Type CastingSometimes you need to use type casts to tell the compiler to convert the type of an expression to another type. For example, suppose that you have the sum of integer values in an integer variable, and would like to compute the average and store it in a variable of type float. In this case, you must tell the compiler to first convert sum tofloat before performing the division.// Older C-style of type castingint sum, n;float average;average = (float) sum / n;

// C++ Style of type castingfloat average;average = float (sum) / n;


Type CastingThe Type Cast Operator

int total=0;float x=1.6;float y=1.7;total = x + y;

If 1.6 + 1.7 = 3.3, then why does total = 3?

total = (int) x + (int) y;result: total equals 2because 1.6 converts to integer 1and 1.7 converts to integer 1Conversion is done before the addition operation


Notes: 77


Character Constants & Initialization

char x;int main(){x='A';cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;cout << x++ << " " << (int) x << endl;}

A 65B 66C 67D 68E 69F 70G 71H 72I 73J 74

Output…Typecast Operator


Integer Division, Negating, Modulus

Dividing Integersint x, y, z;x = 13;y = 3;z = x / y; // z will have 4, not 4.3333

Negating a number or variable ( unary )x = -100; // set x to -100z = -x; // set z to +100

Modulus Arithmeticint x, y, z;x = 13;y = 3;z = x % y; // z will have 1, not 4.3333

In other words 13 divided by 3 is 4 with 1 remainder


Notes: 78


Modulus OperatorModulus Operator: %

The result of the modulus operator (%) is the remainder when the first operand is divided by the second.

Example

In the following example, the modulus operator is used to determine if the numeric value 4 evenly divides into nCenturyYear. If the remainder is zero, the nCenturyYear must be a leap year, so the LeapYearFunction() is executed.

// Example of the modulus operatorint nCentury;

if ((nCenturyYear % 4) == 0) {LeapYearFunction();

}


Modulus Division Example#include <iostream>using namespace std;

int main( ){long x;long rem;char ch;

for (x=0; x<100000; x++){rem = x % 10000;if (rem == 0)

cout << "Here we are at " << x << endl;}

}


Large loop with a display every 10,000


Notes: 79


Review Questions for Chapter 31. What’s the largest number one can represent with a signed integer (2 bytes)?2. What does ‘\n’ mean?3. How many characters can we use to represent a variable name?4. The cout object is used to do what?5. What is wrong with the following C++ statements?

1. cout << This is a test;2. cout << cost_of_goods_sold

6. What I/O Manipulator can we use to print in hex? Octal?7. Are the following variable declarations legal?

double 102inventory;float inventory_102;character ch;int cout;cost float;

1. What is the result of the following code fragment?1. int number=3;2. result = 3*(++number);

2. What does the following statement print?1. int age=32;2. cout << “My age is: “ << age++;

3. Explain typecasting4. How do we represent “not equal” in C++?5. 0x9 is what type of constant?6. 07 is what type of constant?7. The cout.precision(2) member function does what?8. What operators can we use to increment a variable?9. What is the modulus operator?


Homework1. Should have read Chapters 1 and 2 by now2. Read Chapter 3 for next week3. Work on your term paper4. Classroom Group Activity: Break into groups of 2, 3 or

4 students. Do problems 4 on page 161 of the text. (Chapter 3)


Notes: 80


Chapter 3 Summary

Introduction to C++

VariablesAssignment StatementDeclarationscinEscape SequencesFormatting NumbersData TypesVarious OperatorsProgramming Style


Chapter 4

Making Decisions (Selection Structures)

If StatementIf -- ElseSwitch StatementLogical OperatorsExpressionsEnumerated Types


Notes: 81


Insight

Computer Science states that a good language must be able to:

1. Execute a sequence of statements2. Repeat statements until some condition is met3. Test and branch between alternative statements


Logical Operators

Logical Operators&& And|| Or! NotProduces one of two values, TRUE or FALSE== !=<<=>>= Operate on pairs of built in types


Notes: 82


Expression Examples

Code Fragment Examples

if (x < 100)if (x > 0)if (count <= 50)if (count >= 1000)if (ch != ‘Z’)if (status == 1)


If Statement Syntax

Syntaxif (expression)

C++ statement

if (expression){C++ statementsC++ statements

}


Notes: 83


if statementExample

int main(void)

{

float cost;

cout << "Enter Product Cost Less than $100.00: ";

cin >> cost;

if (cost > 100.00)

cout << "Cost Entered Exceeded $100.00 " << cost << endl;

}



Another Example of “if”

int number_in;int max=0;int min = 999999;cout << "Enter a floating point number:";cin >> number_in;

if (number_in > max)max = number_in;

if (number_in < min)min = number_in;


Notes: 84


If - else

A Third Example Showing if -- elseif (remainder == 0)

cout << num2 << " is a factor of " << num1 << endl;else

cout << num2 << " is not a factor of " << num1 << endl;


If Logic is tricky, sometimes …#include <iostream>using namespace std;

int main(){

int testScore;char grade;

cout << "Enter your test score and I will tell you\n";cout << "the letter grade you earned: ";cin >> testScore;

if (testScore < 60)grade = 'F';

if (testScore < 70)grade = 'D';

if (testScore < 80)grade = 'C';

if (testScore < 90)grade = 'B';

if (testScore <= 100)grade = 'A';

cout << "Your grade is " << grade << ".\n";}

Enter your test score and I will tell youthe letter grade you earned: 44Your grade is A.

The order of the logical comparisons is important

Verified 11/23/2003


Notes: 85


If Logic is tricky, sometimes …#include <iostream>using namespace std;

int main(){

int testScore;char grade;

cout << "Enter your test score and I will tell you\n";cout << "the letter grade you earned: ";cin >> testScore;

if (testScore <= 100)grade = 'A';

if (testScore < 90)grade = 'B';

if (testScore < 80)grade = 'C';

if (testScore < 70)grade = 'D';


cout << "Your grade is " << grade << ".\n";}

Enter your test score and I will tell youthe letter grade you earned: 44Your grade is F.

The order of the logical comparisons is important

Verified 11/23/2003


else if construct #include <iostream>using namespace std;

int main(){

int testScore;char grade;bool goodScore = true;

cout << "Enter your numeric test score and I will\n";cout << "tell you the letter grade you earned: ";cin >> testScore;


else if (testScore < 70)grade = 'D';

else if (testScore < 80)grade = 'C';

else if (testScore < 90)grade = 'B';

else if (testScore <= 100)grade = 'A';

elsegoodScore = false;

if (goodScore)cout << "Your grade is " << grade << ".\n";

elsecout << testScore << " is an invalid score.\n";

}

Verified 11/23/2003

Or, we can use the else-if construct

Enter your numeric test score and I will tell you the letter grade you earned: 44Your grade is F.


Notes: 86


Else-if Example (1 of 2)

void main(){

char choice;int months;float charges;

cout << " Health Club Membership Menu\n";cout << "A. Standard Adult Membership\n";cout << "B. Child Membership\n";cout << "C. Senior Citizen Membership\n";cout << "D. Quit the Program\n\n";cout << "Enter your choice: ";cin.get(choice);

cout << fixed << showpoint << setprecision(2);

Continued


Else-if Example (2 of 2)if (choice < 'A' || choice > 'D'){ cout << "The valid choices are A through D.\n";

cout << "Run the program again\n";}else if (choice == 'A'){ cout << "For how many months? ";

cin >> months;charges = months * 40.00;cout << "The total charges are $" << charges << endl;

}else if (choice == 'B'){ cout << "For how many months? ";


}else if (choice == 'C'){ cout << "For how many months? ";


}}


Notes: 87


Nested if statementsvoid main(){

char employed, recentGrad;

cout << "Are you employed? (Y or N) ";cin >> employed;cout << "Have you graduated from college in the past two years? ";cin >> recentGrad;

if (employed == 'Y'){ // Nested if

if (recentGrad == 'Y') // Employed and a recent grad{

cout << "You qualify for the special interest rate.\n";}else // Employed but not a recent grad{

cout << "You must have graduated from ";cout << "college in the past two years to qualify.\n";

}}else // Not employed

cout << "You must be employed to qualify.\n";}


Nested if statementsif (status == SINGLE)

{ if (income <= SINGLE_CUTOFF1)

tax = RATE1 * income;else if (income <= SINGLE_CUTOFF2)

tax = SINGLE_BASE2 + RATE2 * (income - SINGLE_CUTOFF1);else

tax = SINGLE_BASE3 + RATE3 * (income - SINGLE_CUTOFF2);}

else{

if (income <= MARRIED_CUTOFF1)tax = RATE1 * income;

else if (income <= MARRIED_CUTOFF2)tax = MARRIED_BASE2 + RATE2 * (income - MARRIED_CUTOFF1);

elsetax = MARRIED_BASE3 + RATE3 * (income - MARRIED_CUTOFF2);

}


Notes: 88


Logical Operators (or / and)

Example Showing && and ||And operator is &&Or operator is ||

And operatorif (income > 100000 && dependents == 0)

tax_amount = income * 0.33;

Or operatorif (income > 200000 || itemized_deductions > 50000)

call_an_audit = true;


The “AND” Operator

One of the most common mistakes in programming regardless of the language.

Set y=8

((y<3) && (y>7))

So, 8<3 is false8>7 is true

We have, (false && true)

False AND True will evaluate to False when using &&


Notes: 89


The “AND” Operator#include <iostream>using namespace std;

void main(){


cout << "Are you employed? (Y or N)";cin >> employed;cout << "Have you graduated from college ";cout << "in the past two years? ";cin >> recentGrad;

if (employed == 'Y‘ && recentGrad == 'Y'){

cout << "You qualify for the special ";cout << "interest rate.\n";

}else{

cout << "You must be employed and have\n";cout << "graduated from college in the\n";cout << "past two years to qualify.\n";

}}


Logical Or Condition

if ((year == 2000) && (month == 2) && (day == 29)){// Do some leap year stuff..}

if (year == 2000)if (month == 2)

if (day == 29)process_leap_year();

Lazy Evaluation of Boolean OperatorsBoolean Expressions are interpreted left to rightIn an OR condition, scanning stops once a true value is foundIn an AND condition, scanning stops once a false value is found

Which one is faster ?


Notes: 90


Logical Or Conditionvoid main(){


cout << "Are you employed? (Y or N) ";cin >> employed;cout << "Have you graduated from college in the past two years? ";cin >> recentGrad;

if (employed == ‘Y‘ || employed == ‘y‘ ){

if (recentGrad == ‘Y‘ || recentGrad == ‘y’){

cout << "You qualify for the special interest rate.\n";}else {

cout << "You must have graduated from ";cout << "college in the past two years to qualify.\n";

}}else

cout << "You must be employed to qualify.\n";}

Making a previous example, better


The “OR” Operator

ExampleSay we have the following expression and y=8

((y<3) || (y>7))

So, 8<3 is false8>7 is true

We have, (false || true)

False OR True will evaluate to true when using ||


Notes: 91


The “OR” Operator#include <iostream>using namespace std;

void main(){

float income;int years;

cout << "What is your annual income? ";cin >> income;cout << "How many years have you worked at your current job? ";cin >> years;

if (income >= 35000 || years > 5)cout << "You qualify.\n";

else{

cout << "You must earn at least $35,000 or have\n";cout << "been employed for more than 5 years.\n";

}}


Some RulesAND ConditionExp-1 Exp-2 Exp1 && Exp2True True TrueTrue False FalseFalse True FalseFalse False False

OR Condition Exp-1 Exp-2 Exp1 || Exp2True True TrueTrue False TrueFalse True TrueFalse False False


Notes: 92


Some RulesAND Condition (Multiply)Exp-1 Exp-2 Exp1 && Exp21 1 11 0 00 1 00 0 0

OR Condition (Add)Exp-1 Exp-2 Exp1 || Exp21 1 11 0 10 1 10 0 0Think of True as 1 and False as 0


Technical Notes

Logical ANDif ( (x == 5) && (y == 5) )if ( x == 5 && y == 5 )

Logical ORif ( (x == 5) || (y == 5) )if ( x == 5 || y == 5 )

Logical NOTThese are the sameif ( !(x == 5) )if (x != 5)


Notes: 93


Tao of C++

Zero = FALSE, Any other value = TRUE

int x, y, b, c, d;

c=10;d=2;

x = (c > d);y = (d == c);b = (c < 2);


More on Truth in C++

if (value)cout << “It is True”;

if (x + y)cout << “It is True”;

if (pow(a, b))cout << “It is True”;



Notes: 94


More on Truth in C++


What Happens Here ??n = 100;if (n)

cout << n << endl;

What Happens Here ??n = 0;if (n)

cout << n << endl;


Example of TRUE/FALSEint x, y, z;main(void){

x = 10; y = 0;z = -12;

if (x)cout << "X is True: " << x << endl; // Prints

else cout << "X is False:" << x << endl;

if (y)cout << "Y is True: " << y << endl;

else cout << "Y is False:" << y << endl; // Prints

if (z)cout << "Z is True: " << z << endl; // Prints

else cout << "Z is False:" << z << endl;

}


Notes: 95


Not Operator

NOT Operation

Exp !Exp1 00 1

Think of True as 1 and False as 0


Not Operator#include <iostream>using namespace std;

void main(){

float income;int years;

cout << "What is your annual income? ";cin >> income;cout << "How many years at your current job? ";cin >> years;

if (!(income >= 35000 || years > 5)){

cout << "You must earn at least $35,000 or have\n";cout << "been employed for more than 5 years.\n";

}else

cout << "You qualify.\n";}


Notes: 96


De Morgan’s LawWhat if..if (amount > 0 && amount < 1000) …

Now let’s tryif (!(amount > 0 && amount < 1000)) …When it is NOT true that amount > 0 and amount < 100

Augustus de Morgan (1806-1871) states!(A && B) is the same as !A || !B!(A || B) is the same as !A && !B

(A × B) = A + B

(A + B) = A × B

Breeding, Kenneth. (1992). Digital Design Fundamentals.


De Morgan’s LawLet’s prove it:

a b a+b !(a+b) !a !b a × b0 0 0 1 1 1 10 1 1 0 1 0 01 0 1 0 0 1 01 1 1 0 0 0 0

How cool is that?


Notes: 97


Practice

Say count = 1 and limit = 10, evaluate the following:

(count == 1) && (limit < 20)(limit > 20) || (count < 5)!(count == 12)(count == 1) && (limit/count > 7)


Practice

What output will be produced by the following code snippet?

int x = 2;

if (x <= 3)if (x != 2)

cout << “Hey There \n”;else

cout << “Go Man Go \n”;else

cout << “Here we are ! \n”;


Notes: 98


Common Problem

What output will be produced by the following code snippet?

w = 1;if (w = 2)cout << “w equals 2”;


Common Problem

A value lies between 0 and 100 if it is at least 0 and at most 100.

It lies outside the range if it is less than 0 or greater than 100.

There is no golden rule. You just have to think carefully


Notes: 99


Common Problem

Dangling else

How would you fix the following code fragment?

if (richter_value >=0)if (richter_value <=4)

cout << “Harmless”;else

cout << “Negative Value is invalid”;


Quality Tip

Don’t code like this:

if ((d = b * b - 4 * a * c) >= 0) r = sqrt(d);

if (n-- > 0)other C++ statements

Do this instead:d = b * b - 4 * a * c;if (d >= 0)

r=sqrt(d);

if (n-- > 0)other C++ statements


Notes: 100


Switch statementint digit;switch (digit){

case 1: cout << “one”; break;case 2: cout << “two”; break;case 3: cout << “three”; break;case 4: cout << “four”; break;default: cout << “error”; break;

}

Once a condition is “true” the remaining statements are executedCan only be applied to integer and character data typesTest cases can only be constantsA very common error is to omit the breakstatement


Switch statement#include <iostream>using namespace std;

int main( ){

char grade;cout << "Enter your midterm grade and press return: ";cin >> grade;

switch (grade){

case 'A':cout << "Excellent. "

<< "You need not take the final.\n";break;

case 'B':cout << "Very good. ";cout << "Your midterm grade now is "

<< grade << endl;break;

case 'C':cout << "Passing.\n";break;

case 'D':case 'F':

cout << "Not good. “ << "Go study.\n";break;

default:cout << "That is not a possible grade.\n";

}

cout << "End of program.\n";return 0;

}



Notes: 101


Switch Statement#include <iostream>using namespace std;

int main( ){char ch;

cout << "Enter Menu Option(A-C or X to End):";cin >> ch;switch (ch){

case 'A' :cout << "You Chose Menu Item:" << ch << endl; break;

case 'B' :cout << "You Chose Menu Item:" << ch << endl; break;

case 'C' :cout << "You Chose Menu Item:" << ch << endl; break;

case 'X' :break;

default :cout << "Invalid Menu Choice. No Action Taken:" << ch << endl;

}}



Code Blocks

if (day == 29)if (month == 2)

if (year == 2000){total_balance = 0.0;inventory_quantity = 100;cout << day << month << year;}


Notes: 102


Code Blocks

if (day == 29)if (month == 2)

if (year == 2000){double Monthly_Usage;long Julian_Date;Monthly_Usage = consumption * 1.223;Julian_Date = 23456;}

Monthly_Usage is known only to the code block

Considered to have Block Scope


goto statement

Example of goto statementint x;

int main(void){

x = 0; start:cout << “Value of x is “ << x << endl;x++;if (x < 100)

goto start;}


Notes: 103


The Conditional Operator

Syntax: expression ? Expression : expressiona = x > 100 ? 0 : 1;

Is the same asif (x > 100)a = 0;

elsea = 1;


The Conditional Operator

Syntax: expression ? Expression : expressionscore = 90;cout << "Your Grade is " << (score<60 ? "Fail“ : "Passing");

Is the same asif (score < 60)

cout << "Your Grade is Failing;else

cout << "Your Grade is Passing;


Notes: 104


The Conditional Operator#include <iostream>#include <iomanip>using namespace std;

int main(){

const float payRate = 50.0;float hours, charges;

cout << "How many hours were worked? ";cin >> hours;

hours = hours < 5 ? 5 : hours; // Conditionaloperatorcharges = payRate * hours;

cout << fixed << showpoint << setprecision(2);cout << "The charges are $" << charges << endl;return 0;

}


Enumerated Types

enum Roster {Tom, Jim, Sharon, George, Carolyn, Bob};

Creates a data type named Roster// declare a variable of type RosterRoster student;if (student == Sharon)cout << “It’s true”;


Notes: 105


Enumerated Types

Can declare specific values (Integer only)enum Dept {factory=11, sales=20, warehouse=49};

enum Colors {red, orange, yellow=9, green, blue};

Assigned Values are: red=0, orange=1, yellow=9, green=10, blue=11


Floating Point Round Off ErrorsFact of life when using floating point dataDivide 1 by 3 to two decimals, we get 0.33Multiply by 3 and we get 0.99, not 1.00


void main(){

double f= 4.35;int n = (int)(100 * f);if (n == 435)

cout << n << "\n";else

cout << “Something is wrong “ << n << endl;}

Prints Something is wrong 434


Notes: 106


Floating Point Round Off Errors


void main(){double a=6 * 0.666666;if (a == 4.0)

cout << "Hit"; // not true

cout << setprecision(12) << a << "\n\n";}

Prints: 3.999996


Random Number Generator

#include <iostream> // has cout stuff#include <stdlib.h> // Has srand function#include <time.h> // has time functionsusing namespace std;

void main( void ){

cout << "Generate a 100 random numbers\n";srand( (unsigned)time( NULL ) );cout.width(9);cout << rand() << endl;cout.width(9);cout << rand() << endl;cout.width(9);cout << rand() << endl;cout.width(9);cout << rand() << endl;

}

7963

1737

31952

17398



Notes: 107


Let’s See What We Know !!

char x, y, z;main(void){

cout << "Enter a character:";cin >> x;cout << "Enter a character:";cin >> y;cout << "Enter a character:";cin >> z;cout << x << y << z << endl;cout << x + y + z << " Why?" << endl;cout << (int) x << endl;

}

Enter a character:AEnter a character:BEnter a character:CABC198 Why?65

Output…..


Artificial Intelligence

Reasoning abilityI drove the car into the garage and it died.

Woman, without her man, is lostWoman, without her, man is lost

The committee denied the group a parade permit because they feared violence.

The committee denied the group a parade permit because they advocated violence.

How do we know who “they” are?


Notes: 108


Review1. The value of a relational expression is zero if the expression is

__________________?2. What does the following code fragment print?

score = 70;cout << "Your Grade is " <<

(score < 60 ? "Fail“ : "Passing");

3. Discuss the break statement. Where is it used?4. Discuss the continue statement. Where is it used?5. What will the following code fragment print?

Counter = 10;

if (Counter = 11)cout << “Counter equals 11” << endl;

6. Say we have the following expression and y=18, q=20, evaluate the following expression:((y<3) || (y>17) && q == 20)


Homework1. Should have read Chapters 1 through 4 by now2. Read Chapter 5 for next week3. Work on your term paper4. Classroom Group Activity: Break into groups of 2, 3 or



Notes: 109


Chapter 4 Summary

Summary of Selection Structures

If StatementIf -- ElseSwitch StatementLogical OperatorsExpressionsGoto StatementEnumerated Types


Chapter 5

Looping in C++

While LoopsDo LoopsFor…Next LoopsContinue StatementBreak StatementGoto StatementTest for Entrance LoopTest for Exit Loop


Notes: 110


While Loops

Basic Structurewhile (expression)C++ statement

Keeps looping while “expression” is TRUE !Called an “Entry Condition” LoopAlso called a “Test For Entrance” Loop or “Pretest”

LoopWhy?


While Loops

Single-statement bodywhile (Expression)

Single Statement;

Multi-statement bodywhile (Expression)

{Statement-1;Statement-2;Statement-3;Statement-n;}


Notes: 111


While Loop Example 1#include <iostream>using namespace std;

void main(){int number;

while (number != 99){

cout << "Enter a number:";cin >> number;

}}

Verified 04/24/2003


While Loop Example 2#include <iostream>using namespace std;

void main(){char ch;int x;x = 1;

while (ch != '$'){

cout << "Enter a Character:";cin >> ch;cout << "Count:";cout << x++ << " ";cout << ch << endl;

}}

Enter a Character:ACount:1 AEnter a Character:BCount:2 BEnter a Character:CCount:3 CEnter a Character:WCount:4 WEnter a Character:XCount:5 XEnter a Character:#Count:6 #Enter a Character:$Count:7 $

Output

Verified 04/24/2003


Notes: 112


While Loop Example 3#include <iostream>#include <iomanip>using namespace std;

int main(){

int days, count; float total = 0.0; // Initialize accumulator

cout << "For how many days do you have sales figures? ";cin >> days;

count = 1; // Initialize counterwhile (count <= days) {

float sales;cout << "Enter the sales for day " << count << ": ";cin >> sales;total += sales; // Accumulate running totalcount++; // Increment counter

}cout << fixed << showpoint << setprecision(2);cout << "The total sales are $" << total << endl;return 0;

}

Verified 10/24/2003


An Entry Condition Loop

What happens in the following example ?

count = 10;while (count <= 5)

{cout << “Current Count:” << count++ << endl;}

While is tested before execution


Notes: 113


An Entry Condition LoopWhat happens in the following example ?


{cout << “Current Count:” << count++ << endl;}

While is tested before execution


Caution!

What happens in this example ?


cout << “Current Count:” << count << endl;count++;


Notes: 114


Caution!

What happens in this example ?

count = 3;while (count = 5)

cout << “Current Count:” << count++ << endl;


Common Problems Using Loops

Common Problem (Not Incrementing Counter Variables)x=0;while (x<100)

cout << x;

Un-initialized counter variablesint count;while (count>0)

{Statement-1;Statement-2;}

Forgetting braces around multi-statement loops


Notes: 115


Do WhileTwo Formats for the “Do While”do {

statement-1;statement-2;statement-n;

} while (Boolean Expression);

dostatement-1;

while (Boolean Expression);

Keeps looping while “expression” is TRUE !Called an “Exit Condition” LoopAlso called a “Test For Exit” LoopWhy?


Do While

count = 0;do

{cout << “Current Count:” << count << endl;count++;}

while (count <= 5);

An Exit Condition Loop


Notes: 116


Do While#include <iostream>using namespace std;

int main(){

int score1, score2, score3;float average;char again;

do{

cout << "Enter 3 scores and I will average them: ";cin >> score1 >> score2 >> score3;average = (score1 + score2 + score3) / 3.0;cout << "The average is " << average << ".\n";cout << "Do you want to average another set? (Y/N) ";cin >> again;

} while (again == 'Y' || again == 'y');return 0;

}


Test for Entrance or Exit

Test for exitcount = 9;do

cout << “Current Count:” << count++ << endl;while (count < 5);

Test for entrancecount = 9;while (count < 5)

cout << “Current Count:” << count++ << endl;


Notes: 117


When to Use Do Loops

DO use do...while when you want to ensure the loop is executed at least once. DO use while loops when you want to skip the loop if the condition is false. DOtest all loops to make sure they do what you expect.

More Complicated while StatementsThe condition tested by a while loop can be as complex as any legal C++ expression. This can include expressions produced using the logical && (AND), || (OR), and ! (NOT) operators


Determine the Min and Max on the Fly

double number_in, max, min; int i=0;

Void main(){

// Establish test variablesmin=9999999.99;max=0.0;

// Loop 7 times and prompt for numbers// Test each number entered against test variables// Set test variables to new maximum or minimum valueswhile (i < 8){

cout << i++ << ": Enter a floating point number:";cin >> number_in;if (number_in > max)

max = number_in;if (number_in < min)

min = number_in;}

// Print the resultscout << "Highest number entered is: " << max;cout << " Lowest number entered is: " << min << endl;


Notes: 118


The “For Loop”

General Syntax:for (initialize; test; update action)

Other C++ statements

The loop is repeated until the test is falseExamples:

for (n=0; n<100; n++)cout << n << “\n”;

for (n=100; n>10; n--)cout << n << “\n”;


For Loop

Single-statement bodyfor (Initialization; Boolean Test; Update Action)

Single Statement;

Multi-statement bodyfor (Initialization; Boolean Test; Update Action)

{Statement-1;Statement-2;Statement-3;Statement-n;}


Notes: 119


For Loop

Examplesfor (count=0; count<1000; count++)

{Statement-1;Statement-2;Statement-n;}

for (int i=110; i<120; i=i+1){Statement-1;Statement-2;Statement-n;}


For Loop

Examplesfor (count=0; count<1000 && x>10; count++)

Statement-1;

for (int i=110; i<180; i=i+10){Statement-1;Statement-2;Statement-n;}


Notes: 120


For Loop

Common Problemfor (count=0; count<1000 && x>10; count++);

Statement-1;

for (int i=110; i<120; i=i+1);{Statement-1;Statement-2;}

No Semi Colons Here


Multi-parameter for LoopsThe for StatementThe syntax for the for statement is as follows:for (initialization; test; action)

statement;

#include <iostream>#include <iomanip>using namespace std;long x,y,z;

void main ()

{for (x=0,y=0,z=0; x<10 && y<100 || z<50; x++, y=y+10, z=z+2)

{cout << setw(8) << x << setw(8) << y << setw(8) << z << endl;}

}


Notes: 121


Null statements in for loops


void main(){

int counter = 0;

for( ; counter < 5; ){counter++;cout << "Looping! ";

}

cout << "\nCounter: " << counter << ".\n";}

output: Looping! Looping! Looping! Looping! Looping!Counter: 5.

Verified 04/24/2003


Nested Loops


int x, y;

main(){for (y=0; y<5; y++)

for (x=0; x<5; x++)cout << y << " " << x << endl;

}

Output0 00 10 20 30 41 01 11 21 31 42 02 12 22 32 43 03 13 23 33 44 04 14 24 34 4



Notes: 122


Nested Loops#include <iostream>using namespace std;

int x, y;

main(){

for (y=0; y<5; y++){for (x=0; x<5; x++)

{cout << x << " " << y << endl;}

}

}

Same as previous example but with braces showing the nesting


continue statement

Example of continue statement


int x;

int main(void){x = 0; while (x < 20)

{x++;if (x == 1 || x == 2)

continue;cout << "Value of x is " << x << endl;

}}

Continue forces the next iteration of the loop.

Code verified 6/21/01

Value of x is 3Value of x is 4Value of x is 5Value of x is 6Value of x is 7Value of x is 8Value of x is 9Value of x is 10Value of x is 11Value of x is 12Value of x is 13Value of x is 14Value of x is 15Value of x is 16Value of x is 17Value of x is 18Value of x is 19Value of x is 20

Generated Output


Notes: 123


Break StatementExamplecount = 100;while (1)

{if (count == 0)

break;count--;cout << count << endl;}

While is always evaluated to trueBreak used to “Get Out”Count is is used then decremented


continue and break

continue and breakAt times you'll want to return to the top of a while loop before the entire set of statements in the while loop is executed. The continue statement jumps back to the top of the loop.At other times, you may want to exit the loop before the exit conditions are met. The break statement immediately exits the while loop, and program execution resumes after the closing brace.


Notes: 124


Loops are Great for Data Validation

int number;do{

cout << "Enter a number between 1 and 100: ";cin >> number;

if (number < 1 || number > 100)cout << "Invalid Number Entered! Try Again.\n\n";

}while (number < 1 || number > 100);


Loops in Review

1. What looping construct is used for a “Test for Entrance” Loop?

2. What looping construct is used for a “Test for Exit”loop?

3. The “for-loop” has _____ formal parameters?4. What C++ statement can we use to get out of a

switch statement or a while loop?5. What C++ statement can we use to force the next

iteration of a while loop?6. While-loops, While-Loops, Do-while Loops and For

Loops all have a similar form factor. What is it?


Notes: 125


Homework1. Should have read Chapters 1 through 5 by now2. Read Chapter 6 for next week3. Work on your term paper4. Classroom Group Activity: Break into groups of 2, 3 or



Chapter 5 Summary

Summary of Looping Structures

While loopsFor loopsDo – WhileNested LoopsTest for EntranceTest for ExitCounters


Notes: 126


Section 4b

Encryption Fundamentals

Brute Force attackCaesar’s CipherXOR CipherCode ObfuscationVigenère CipherRandom Mono-alphabet Cipher


Data Security Through EncryptionThe process of scrambling data in a file so no one can interpret the

data unless they have a special software key

The Federal Data Encryption Standard (DES) used to be a good algorithm for most commercial applications. But the Government never did trust the DES to protect its own classified data, because the DES key length is only 56 bits, short enough for a brute force attack.

56 bit = 256-1 = 7.205757404x1016 or 72,057,574,040,000,00064 bit = 256-1 = 1.844674407x1019 or 18,446,744,070,000,000,000128 bit = 2128-1 = 3.402823669x1038 or …

DES 64-bitTriple DES 128-bitRijndael 64-bitRC2 64-bit


Notes: 127


Data Security Through Encryption

What is a brute force attack?Take the data in question and continue to

try different values for keys until you get a meaningful result

Brute force method is used to crack Unix passwords

Software called Satan

Take a copy of the Unix Password fileUse a dictionary of over a million words to

try each password


Basic Encryption (Caesar’s Cipher)

The process of scrambling data in a file so no one can interpret the data unless they have a special software key

Basic encryption is easyUse a key from 1 to 25 and make an offset from each letter.Called the Caesar CipherSay, we choose 4 as the keyA becomes E, B becomes F, C becomes G, etcAll sorts of schemes for short runs of dataSay, we have a 10-byte product keyAdd 1 to the 1st byte, 2 to the 2nd, 3 to the 3rd, and so on


Notes: 128


Basic Encryption (Caesar’s Cipher)

Key of 3A B C D E F G H I J K L M N O P Q R S T U V W X Y ZD E F G H I J K L M N O P Q R S T U V W X Y Z A B C

MEET ME AT MIDNIGHT becomesPHHW PH DW PLGQLJKW

Easy to crackLinguistic patterns are obviousE is the most common letter, followed by t, a,

o, nT is the most common letter to begin a word


Encryption – Random Mono-Alphabet

Random Mono-alphabet CipherPick a word to use as the key, FEATHER, for exampleRemove duplicate letters leaving, FEATHRUse FEATHR to start then use remaining letters starting from

right to left

ABCDEFGHIJKLMNOPQRSTUVWXYZFEATHRZYXWVUSQPONMLKJIGDCB


Notes: 129


Encryption -- Vigenère Cipher

Vigenère CipherPick a word for the key, say TIGERUse the ‘T’ as the starting offset

ABCDEFGHIJKLMNOPQRSTUVWXYZTUVWXYZABCDEFGHIJKLMNOPQRS

Then do it again using ‘I’ as the starting offsetABCDEFGHIJKLMNOPQRSTUVWXYZIJKLMNOPQRSTUVWXYZABCDEFGH

Then again using G and then E and RThe word CAT becomes

VTMDBU

And so on..


Basic Encryption (XOR Cipher)

Take each byte and XOR it with a number, say 6, for example

A 65 01000001XOR 06 00000110G 72 01000111


Notes: 130



How do you do this with C++?

char ch=‘A’char key=6;char newchar;

newchar = ch ^ key;cout << newchar;

Exclusive OR



How would you process an XOR encrypted file without knowing the specific key?

1. Open the message or file2. Read each byte and XOR it with 1 and

display the message.3. Loop from 1 through 255 and try each key.4. Display the message using different key

values until you obtain a readable message


Notes: 131


XOR Cipher Example

#include <iostream>using namespace std;void main(void){

const int MAX = 24;char product_key[MAX] ="ABCD1234-2004";char encrypted[MAX];char decrypted[MAX];int length, i, key=13;

for (i=0; i<MAX; i++){

encrypted[i]='\0';decrypted[i]='\0';

}

length = strlen(product_key);

for (i=0; i<length; i++)encrypted[i] = product_key[i] ^ key;

cout << "Original Message:" << product_key << endl;cout << " Encrypted:" << encrypted << endl << endl;

for (i=0; i<length; i++)decrypted[i] = encrypted[i] ^ key;

cout << " Decrypted:" << decrypted << endl;}

Original Message:ABCD1234-2004Encrypted:LONI<?>9 ?==9

Decrypted:ABCD1234-2004



CERT Coordination Center

http://www.cert.org/advisories/Carnegie Melon University Software Engineering

InstituteSeveral hundred per year are publishedIt is stated that 85% of the CERT advisories could have

been prevented by using cryptographyBlack-box tests, White-box tests, Red Team Testing


Notes: 132


Encryption Summary

Summary of Encryption

Brute Force attackCaesar’s CipherXOR CipherCode ObfuscationVigenère CipherRandom Mono-alphabet Cipher


Chapter 6

Functions

Top Down DesignPredefined FunctionsUser-Defined FunctionsBlack Box AnalogyScopeCall by ValueCall by ReferenceFunction Overloading


Notes: 133


Functions

What is a function?1. Who can explain what a function is in terms of

mathematics?2. What is reusable code?3. Why do we create and use software functions?4. Who can describe the difference between

programmer defined and built-in functions?


Functions

What is a function?

A function is a self-contained unit of program code designed to accomplish a particular task.Also known as subroutines or procedures in other languages.Saves you from repetitious programming.Black Box Concept.


Notes: 134


Black Box Effect of Functions

Black Box EffectThevenin’s Theorem in Engineering

Pass in Some Data Function Return A Result


Analogous to a Mathematics Function

y = mx + bWhere

y is the return valuem, x and b are passed arguments

Arguments can be numeric, character, etcReturn values can be numeric or character


Notes: 135


Functions - Syntax

Function Definition:return_type function_name (arg1_type arg-1, arg2_type

arg-2, arg-n..){

C++ statements..return(value);

}


Functions – 3 PartsThe Prototype:return_type function_name(arguments);

Function Call:receiving_variable = function_name(arguments);

Function Definition:return_type function_name(arguments){

C++ statements;return(value);

}


Notes: 136


Functions - Syntax

Example showing integer return valueint result;Prototype:int squared(int x);

Calling a Function:result = squared(10);

Function:int squared(int x){

x=x*x;return(x);

}


Declaring a Function

There are three ways to declare a function:

1. Write your prototype into a file, and then use the #include directive to include it in your program.

2. Write the prototype into the file in which your function is used.

3. Define the function before it is called by any other function. When you do this, the definition acts as its own declaration.


Notes: 137


Prototype Variations

Prototype Variationsint squared(int x);float cubed(float z);char status(char ch);void display(int x, int y, int z);void printone(char c, int x, float q);void swap(long x, long y);bool thing(void);double test_for_whatever(int, float, bool);

Compiler looks for the number of arguments and the argument type.

A prototype defines to the compiler the functions of a given program, its arguments and its return data type


Functions - No Arguments

#include <iostream>using namespace std;void put_asterisk(void);

int i;

int main(){

put_asterisk();put_asterisk();put_asterisk();return(0);

}

void put_asterisk(){

cout << “*”;}

Note: void means no argument expected

Note

Passed Nothing

Returns Nothing


Notes: 138


Functions - Global Variables// code verified 10/31/2002#include <iostream>using namespace std;void put_asterisk(char ch); // prototypeint i;char ch4='!';

void main(){ char ch1='*';char ch2='$';char ch3='A';

put_asterisk(ch1); // function callput_asterisk(ch2);put_asterisk(ch3);

}

// Function to print the character that is passedvoid put_asterisk(char ch) // definition{

cout << ch << ch4 << endl;}


Generated Output*!$!A!


Functions - Return Values// code verified 10/31/2002include <iostream>using namespace std;float num1, num2, ans;float calc(float a, float b); // Function prototype

void main(void){

num1=12.1;num2=9.9;ans=calc(num1, num2);cout << "The returned value is: " << ans <<endl;

}

// Define the actual functionfloat calc(float num1, float num2){

float answer;cout << "The passed values are: " << num1 << " " << num2 << endl;answer = (num1-num2)/(num1*num2);return(answer);

}

Generated OutputThe passed values are: 12.1 9.9The returned value is: 0.0183655


Notes: 139


Functions - Return Values#include <iostream>#include <iomanip>using namespace std;

float getRadius();float square(float);

void main(){

const float pi = 3.14159;float rad;

cout << fixed << showpoint << setprecision(2);cout << "This program calculates the area of a circle.\n";rad = getRadius();cout << "The area is " << pi * square(rad) << endl;

}

float getRadius(){

float radius;cout << "Enter the radius of the circle: ";cin >> radius;return radius;

}

float square(float number){

return number * number;}


Pre-defined Functions

int x=25;float y=3.2;

sqrt(x) returns 5pow(2, 5) returns 32abs(-9) returns 9labs(-90000) returns 90000fabs(-7.56) returns 7.56ceil(y) returns 4.0 rounded upceil(3.9) returns 4.0 rounded upfloor(y) returns 3.0 rounded downfloor(3.9) returns 3.0 rounded down


Notes: 140


C++ Is Very Function Oriented

Examples of Function Calls:display_totals();display_totals(amt1, amt2);x = compute_total(amt1, amt2);fopen(filename,”r”);status=fopen(filename,”r”);printf(“This is C++ at its Finest.“);


Using Functions as Parameters to Functions

Although it is legal for one function to take as a parameter a second function that returns a value, it can make for code that is hard to read and hard to debug.

As an example, say you have the functions double(), triple(), square(), and cube(), each of which returns a value. You could write

Answer = (double_it(triple(square(cube(myValue)))));

This statement takes a variable, myValue, and passes it as an argument to the function cube(), whose return value is passed asan argument to the function square(), whose return value is in turn passed to triple(), and that return value is passed to double(). The return value of this doubled, tripled, squared, and cubed number is now passed to Answer.

It is difficult to be certain what this code does (was the value tripled before or after it was squared?), and if the answer is wrong it will be hard to figure out which function failed.


Notes: 141


System Function v. Programmer Defined// code verified 10/31/2002#include <iostream>using namespace std;int y = 60;int displaytext(void);void main(void){

int x = 100;cout << "Displaytext Returns " << displaytext();cout << endl;

}

// Programmer defined functiondisplaytext(){

int x = 90;cout << "x=" << x << " y=" << y << endl;return(x);

}

Return and main are system functions

Outputx=90 y=60DisplaytextReturns 90


Default Arguments#include <iostream>using namespace std;

void displayStars(int = 10, int = 1);

void main(){

displayStars(); // Uses default values cols and rowscout << endl;displayStars(5); // Uses 5 for cols and default value for rowscout << endl;displayStars(7, 3); // Uses 7 for cols and 3 for rows

}

void displayStars(int cols, int rows){

for (int down = 0; down < rows; down++){

for (int across = 0; across < cols; across++)cout << '*';

cout << endl;}

}


Notes: 142


Graphical RepresentationWindows

or

DOSFunction A

Function D

Function CFunction B

Main()


Variable Scope// code verified 10/31/2002#include <iostream>int y = 60; // Global Variableint displaytext(int abc); // prototype scopevoid main(void){

int x = 10; // Local to the maincout << "Displaytext Returns " << displaytext(x);cout << endl;

}

// Programmer defined functiondisplaytext(int abc){

int x = 90; // local to the functioncout << "x=" << x << " y=" << y << " abc=" << abc << endl;return(x);

}

Generated Outputx=90 y=60 abc=10Displaytext Returns 90


Notes: 143


Variable Scope

File Scope GlobalFunction Scope Local to functionBlock Scope Local to surrounding blockPrototype Scope Local to prototype only


Local and Global VariablesLocal Variables

Not only can you pass in variables to the function, but you also can declare variables within the body of the function. This is done using local variables, so named because they exist only locally within the function itself. When the function returns, the localvariables are no longer available.

Local variables are defined like any other variables. The parameters passed in to the function are also considered local variables and can be used exactly as if they had been defined within the body of the function.

Global VariablesVariables defined outside of any function have global scope and

thus are available from any function in the program, including main().

Local variables with the same name as global variables do not change the global variables. A local variable with the same nameas a global variable hides the global variable, however. If a function has a variable with the same name as a global variable,the name refers to the local variable--not the global--when used within the function.


Notes: 144


Variable Scope#include <iostream>int cube_it(int x); // prototype scope

int i=100; // global scope

// passed argv from DOS command line// passed environment variables in envpint main(int argc, char *argv[], char *envp[]){

int cost_of_goods_sold=0.0; // local to the mainint i=0;{

int i=10; // local to blockcout << cube_it(i) << endl;return(0);

}}

int cube_it(int c){

int cubed_value=0; // local to the functioncubed_value=c*c*c;return(cubed_value);

} Code Verified 10/31/2001


The Return Statement


double cube_it(double x);

int main(void){

double cube;cube = cube_it(10.0);cout << cube << endl << endl;return(0);

}

double cube_it(double c){

double cubed_value=0.0;cubed_value=c*c*c;return(cubed_value);

}



Notes: 145


Return Values

Several forms of return statements

return 5; // returns 5return (5); // returns 5return (x > 5); // returns true if x > 5return (MyFunction()); // calls MyFunctionreturn; // simply bails out


Return Statement in a Void Function

void print_headings(long kwh){

cout << "Monthly Usage Report " << endl;cout << "-------------------------" << endl;cout << "Customer KWH " << endl;

if (kwh == 0.0)return;

elsecout << customer_name << " " << kwh << endl;

}


Notes: 146


Automatic Local Variables (Default)

Each call to a function creates a new copy of all the variables declared in the function.

This is automatic and can be stated so on the declarations with the auto keyword

void showVariable(){auto int myNum=0; // default

cout << "StatNum is " << myNum << endl;myNum++;

}


Automatic Local Variables (Default)#include <iostream>using namespace std;

void showVariable();

int main(){

for (int count = 0; count < 9; count++)showVariable();

return 0;}

void showVariable(){

int myNum=0;


}

Generated Output:StatNum is 0StatNum is 0StatNum is 0StatNum is 0StatNum is 0StatNum is 0StatNum is 0StatNum is 0StatNum is 0


Notes: 147


Static Local Variables#include <iostream>using namespace std;

void showVariable();

int main(){

for (int count = 0; count < 9; count++)showVariable();

return 0;}

void showVariable(){

static int myNum=0;


}

Generated Output:StatNum is 0StatNum is 1StatNum is 2StatNum is 3StatNum is 4StatNum is 5StatNum is 6StatNum is 7StatNum is 8


Break


Notes: 148


Call by Value// code verified 10/31/2002int a,b;void swap(int x, int y);

void main(void){

a=100;b=200;cout << "a=" << a << endl;cout << "b=" << b << endl;swap(a, b);cout << "a=" << a << endl;cout << "b=" << b << endl;

}

void swap(int x, int y){

int hold;hold=x;x=y;y=hold;

}

Generated Outputa=100b=200a=100b=200

OutputA=100B=200A=100B=200

Arguments NOT Affected


Call By Reference Example// Example of Call by Reference Functions#include <iostream>using namespace std;

void get_input(int& n1, int& n2); // Prototype parameters

void main(void){

int first_num, second_num;get_input(first_num, second_num);cout << "Number One Entered:" << first_num << endl;cout << "Number Two Entered:" << second_num << endl;

}

// Get user input// prompt user for 2 integers// Pass values back through passed argumentsvoid get_input(int& num1, int& num2){

cout << "Enter Number 1:";cin >> num1;cout << "Enter Number 2:";cin >> num2;

}

Actual values of first_num and second_num are modified within the function and the arguments themselves are modified.



Notes: 149


Call By Value Example// Example of Call by Value Functions#include <iostream>using namespace std;void get_input(int n1, int n2); // Prototype, formal parameters

void main(void){

int first_num, second_num;get_input(first_num, second_num);cout << "Number One Entered:" << first_num << endl;cout << "Number Two Entered:" << second_num << endl;

}

// Get user input// Prompt user for 2 integers// Attempt to pass values back through passed argumentsvoid get_input(int num1, int num2){

cout << "Enter Number 1:";cin >> num1;cout << "Enter Number 2:";cin >> num2;

}

Call by Value is the default function calling method which does NOT modify the arguments. Data is protected.



Swap Examplevoid get_input(int& n1, int& n2); // Prototype, formal parametersvoid swap(int& n1, int& n2);

void main(void){

int first_num, second_num;get_input(first_num, second_num);swap(first_num, second_num);cout << "Number One Entered:" << first_num << endl;cout << "Number Two Entered:" << second_num << endl;

}

// Get user input// prompt user for 2 integers// Pass values back through passed argumentsvoid get_input(int& num1, int& num2){

cout << "Enter Number One:";cin >> num1;cout << "Enter Number Two:";cin >> num2;

}

// Swap the values that are passed// Pass values back through passed argumentsvoid swap(int& num1, int& num2){

int temp;temp = num1;num1 = num2;num2 = temp;

}



Notes: 150


Simulate a Roll of a Die (1 of 2)#include <iostream> // has cout stuff#include <stdlib.h> // Has srand function#include <time.h> // has time functions#include <iomanip> // for setw

using namespace std;const int MAX=1000000;

unsigned x, seed; int roll;double percent;unsigned arr[6];

void main( void ){

// Housekeeping, initialize arrays, etcfor (x=0; x<6; x++)

arr[x]=0;

cout << "Simulate 10 rolls of a die\n";seed = (unsigned)time( NULL );cout << "Seed is " << seed;

// First, print out 30 die throwssrand(seed);for(x = 0; x<30; x++ ){

roll = rand() % 6 + 1;cout << roll << endl;

}

Simulate 30 rolls of a dieSeed is 1099104137211464355465622655141111222263



Simulate a roll of a die (2 of 2)

// Next simulate 1 million throws and check the distributionsrand(seed);for(x = 0; x<MAX; x++ ){

roll = rand() % 6;arr[roll]++;

}

// Calculate and display distribution and percentagescout << "Die Count Percent\n";for (x=0; x<6; x++){

percent = ((double) arr[x] / (double) MAX) * 100.00;cout << setw(2) << x+1 << setw(9)

<< arr[x] << setprecision(4) << setw(9) << percent << endl;

}} Die Count Percent

1 166191 16.622 167280 16.733 166278 16.634 166102 16.615 167434 16.746 166715 16.67



Notes: 151


Function Overloading

Functions with the same name but with different argument lists

Example: Say we want to square a number, but want to pass it different types of variables. (long, int, float, double, for instance)

In Standard C and C++, the function prototypes look like:int square_int(int);long square_long(long);float square_float(float);


Function Overloading// code verified 10/31/2002#include <iostream>using namespace std;

int cube(int);float cube(float);

int int_input;float flt_input;

void main(void){

cout << "Enter an integer to cube:";cin >> int_input;cout << "Enter a float to cube:";cin >> flt_input;cout << int_input << " cubed is " << cube(int_input) << endl;cout << flt_input << " cubed is " << cube(flt_input) << endl;

}

int cube(int n) {return(n*n*n);

}

float cube(float n) {return(n*n*n);

}


Notes: 152


Function Overloading (Polymorphism)#include <iostream>using namespace std;long vector;int counter;float standard_deviation;double mass_of_the_sun;

// Function Prototypesint square(int);long square(long);float square(float);double square(double;

int main(void){

square(counter);square(standard_deviation);square(vector);square(mass_of_the_sun);

}

Note same function name but different argument types

Called Polymorphism


Function Overloadingint square(int q) {

return(q*q);}

float square(float q) {return(q*q);

}

long square(long q) {return(q*q);}

double square(double q) {return(q*q);

}

Note here, in C++, the function names are all the same. Only the return types and argument lists are different.


Notes: 153


Function Overloadingint mean(int n1, int n2, int n3);int mean(int n1, int n2, int n3, int n4);

int main(void){

m = mean(2, 4, 6);m = mean(100, 120, 233, 444);return(0);

}

int mean(int n1, int n2, int n3) {return((n1 + n2 + n3)/3);

}

int mean(int n1, int n2, int n3, int n4) {return((n1 + n2 + n3 + n4)/4);

}


Function Overloadingbool deposit(double amt, string acct);bool deposit(string date, double amt, string acct);

int main(void){

deposit(date, amount, account);deposit(amount, account);

}

bool deposit(string date, double amt, string acct) {return(true);

}

bool deposit(double amt, string acct) {date = todays_date;return(true);

}


Notes: 154


Function Templates, Embedded#include <iostream>using namespace std;

// Get input data templatetemplate <class T1>T1 square(T1 number){

return(number * number);}

void main(void){

int num0=10;short num1=10;long num2=10L;double num3=10.21;float num4=10.21F;

cout << num0 << " Squared is " << square(num0) << endl;cout << num1 << " Squared is " << square(num1) << endl;cout << num2 << " Squared is " << square(num2) << endl;cout << num3 << " Squared is " << square(num3) << endl;cout << num4 << " Squared is " << square(num4) << endl;

cout << "10 Squared is " << square(10) << endl;cout << "10.21 Squared is " << square(10.21) << endl;cout << "10.21F Squared is " << square(10.21F) << endl;

}

Code Tested 10/03/2004


Function Templates, Header Files#include <iostream>using namespace std;

#include <c:/progs/square_template.h> // squared template

// Main Logic Areavoid main(void){

int num0=10;short num1=10;long num2=10L;double num3=10.21;float num4=10.21F;

cout << num0 << " Squared is " << square(num0) << endl;cout << num1 << " Squared is " << square(num1) << endl;cout << num2 << " Squared is " << square(num2) << endl;cout << num3 << " Squared is " << square(num3) << endl;cout << num4 << " Squared is " << square(num4) << endl;

cout << "10 Squared is " << square(10) << endl;cout << "10.21 Squared is " << square(10.21) << endl;cout << "10.21F Squared is " << square(10.21F) << endl;

cout << "Completed...\n\n";}


// Get input data templatetemplate <class T1>

T1 square(T1 number){

T1 result;result = number * number;

return(result);}


Notes: 155


Function Templates, Header Files#include <iostream>#include <iomanip>

using namespace std;

#include <c:/progs/Swap_template.h> // squared template


int num1=1000;int num2=2000;

cout << setw(12) << num1 << setw(12) << num2 << endl;swap(num1, num2);cout << setw(12) << num1 << setw(12) << num2 << endl;

cout << "Test Completed...\n\n";}


//Get input data templatetemplate <class T1>void square(T1 &x, T1 &y){

T1 temp;temp = x;x = y;y = temp;

}


Function Templates, System Supplied

#include <iostream>#include <iomanip>#include <algorithm> // system supplied swap template



int num1=1000;int num2=2000;

cout << setw(12) << num1 << setw(12) << num2 << endl;swap(num1, num2);cout << setw(12) << num1 << setw(12) << num2 << endl;

cout << "Test Completed...\n\n";}



Notes: 156


Quick Review of Functions#include <iostream>using namespace std;int cube_it(int x);

int main(void){

int x = 10;cout << “Initial:” << x << endl;

cube_it(x);

return(0);}

int cube_it(int x){

int value;value= x * x * x;cout << value;return(value);

}


Review Questions1. What are the three main pieces you need to consider when

designing and using a function?2. What type of arguments can be passed to a C++ function?3. Is there a particular order to the arguments passed to a

function?4. What is the scope of a global variable?5. The ceil() function is known as what type of C++ function?6. The “return” function, when used without an argument, is used

to __________?7. Which “Call by” method can be used to modify a function’s

arguments?


Notes: 157


Homework1. Should have read Chapters 1 through 6 by now2. Read Chapter 7 for next week3. Work on your term paper

4. Classroom Group Activity: Break into groups of 2, 3 or 4 students. Do problem 2 on page 386 of the text. (Chapter 6)


Chapter 6 Summary

C++ Functions

Built-in FunctionsUser Defined FunctionsDefinitionsPrototypesCalling by ReferenceCalling by ValueOverloading


Notes: 158


Chapter 7Data Structures and Classes

ClassesEncapsulationConstructorsStruct Type


Data Structures

We have already studied: char, long, double, float data types. These are system defined data types.

Now we are going to add user defined data types, called abstract data types. This is where we bring together the primitive data types into data types of our own design.


Notes: 159


Data Structures

struct CDAccount // Structure Tag or Template{

double balance; // Member Namesdouble interest_rate;int term;

};

struct CDAccount { // Structure Tag or Templatedouble balance; // Member Namesdouble interest_rate;int term; };


Data Structures

struct CDAccount // Structure Tag or Template{

double balance; // Member Namesdouble interest_rate;int term;

};

int main(void){CDAccount my_account, your_account; // Structure Variablesfloat cost_of_goods_sold;}

Define the data type

Define the variable



Notes: 160


Data Structures

struct Time // Structure Tag or Template{

int hour;int minute;int seconds;

};

int main(void){Time now; // structure variable}



Data Structures#include <iostream>#include <cmath>#include <iomanip>using namespace std;

struct Circle // Structure Tag or Template{

double radius;double diameter;double area;

};

const double pi=3.14159;

void main(void){Circle c; // structure variable

// Get user inputcout << "Enter the diameter:";cin >> c.diameter;

// Do calculationsc.radius = c.diameter / 2;c.area = pi * pow(c.radius, 2.0);

// Do Outputcout << fixed << showpoint << setprecision(2);cout << "Radius: " << setw(6) << c.radius << endl;cout << " Area: " << setw(6) << c.area << endl;}



Notes: 161


DOT OperatorSyntax:Structure_Variable_Name.Member_Variable_NameExample:struct StudentRecord{int student_number;int student_age;char student_grade;};

int main(void){StudentRecord your_record;your_record.student_number = 20082;your_record.student_grade = ‘A’;your_record.student_age=32;

}



Initializing a Structurestruct StudentRecord{int student_number;int student_age;char student_grade;};

int main(void){

StudentRecord your_record={12345, 32, ‘A’};// or

your_record.student_number=12345;your_record.student_age=32;your_record.student_grade=‘A’;

}



Notes: 162


Data Structures#include <iostream>using namespace std;

struct book { // Structure Templatechar title[30];char author[25];int quantity;float cost;};

void main(void){book library; // Structure Variable

cout << " Enter Book Title:";cin >> library.title;cout << "Enter Authors Name:";cin >> library.author;cout << " Enter Recent Cost:";cin >> library.cost;

cout << library.title << " "; cout << library.author << " "; cout << library.cost << endl;

}Code verified 11/04/01


Alternate Way of Declaring Structure Variables

struct book { // Structure Templatechar title[30];char author[25];int quantity;float cost;} library; // Structure Variable



Notes: 163


Passing Structure Members to Functions#include <iostream>using namespace std;struct book

{ // Structure Templatechar title[30];char author[25];int quantity;float cost;} library; // Structure Variable

float invcost(int, float);

int main(void){

cout << "Enter Book Quantity:";cin >> library.quantity;cout << "Enter Book Cost:";cin >> library.cost;cout << invcost(library.quantity, library.cost) << endl;return(0);

}

// Function to compute inventory costfloat invcost(int quan, float cost){

return(quan * cost);}

Validated 7/13/2001



struct book { // Structure Templatechar title[30];char author[25];int quantity;float cost;} library; // Structure Variable

// Prototypesfloat calculate(float, int);void get_input(float&, int&);

int main(void){

get_input(library.cost, library.quantity);cout << calculate(library.cost, library.quantity) << endl;return(0);

}

float calculate(float cost, int quan){

return(quan * cost);}

void get_input(float& c, int& q){

cout << "Enter Book Quantity:";cin >> q;cout << "Enter Book Cost:";cin >> c;

}Validated 7/13/2001

Passing Structure Members to Functions


Notes: 164


struct Circle{

float radius;float diameter;float area;

};

Circle getInfo();

const double pi = 3.14159;

void main(){

Circle c1, c2;

c1 = getInfo();c2 = getInfo();

c1.area = pi * pow(c1.radius, 2.0);c2.area = pi * pow(c2.radius, 2.0);

cout << fixed << showpoint << setprecision(2);cout << "\nThe radius and area of the circles are\n";cout << "Circle 1 -- Radius: " << setw(6) << c1.radius

<< " Area: " << setw(6) << c1.area << endl;cout << "Circle 2 -- Radius: " << setw(6) << c2.radius

<< " Area: " << setw(6) << c2.area << endl;}

Validated 11/22/2003

Returning a Structure From a Function (1 of 2)

1 of 2


Circle getInfo() {

Circle round; cout << "Enter the diameter of a circle: ";cin >> round.diameter;round.radius = round.diameter / 2;return round;

}


Returning a Structure From a Function (2 of 2)

Enter the diameter of a circle: 32Enter the diameter of a circle: 43

The radius and area of the circles areCircle 1 -- Radius: 16.00 Area: 804.25Circle 2 -- Radius: 21.50 Area: 1452.20


Notes: 165


Nested Structuresstruct ChkDate

{int year;int month;int day; }; // Structure Variable

struct book { // Structure Templatechar title[30];char author[25];int quantity;float cost;ChkDate check_out;}; // Structure Variable

book library;ChkDate date;

int main(void){

ChkDate newdate = {2000, 02, 22}; // initializingcout << library.check_out.day;cout << date.year << endl;

}



Nested Structuresstruct AnnualCostInfo{

float food, medical, license, misc;};

struct PetInfo{

string name;string type;int age;AnnualCostInfo cost;

};

void main(){

PetInfo pet; // Define a structure variable

pet.name = "Sassy";pet.type = "cat";pet.age = 5;pet.cost.food = 250.00;pet.cost.medical = 150.00;pet.cost.license = 7.00;pet.cost.misc = 50.00;

cout << fixed << showpoint << setprecision(2);cout << "Annual costs for my " << pet.age << "-year-old " << pet.type << " " << pet.name << " are $"

<< (pet.cost.food + pet.cost.medical + pet.cost.license + pet.cost.misc) << endl;

}


Annual costs for my 5-year-old cat Sassy are $457.00


Notes: 166


Structure Constructorsstruct Employee{

int employees;int year;float payrate;

Employee(){

employees =120;year =2004;payrate =25.55;

}};

void main(void){

Employee emp;cout << " Employees: “ << emp.employees << endl;cout << " Fiscal Year: “ << emp.year << endl;cout << "Starting Rate: “ << emp.payrate << endl;

}


Employees: 120Fiscal Year: 2004

Starting Rate: 25.55


Structure Constructors#include <iostream.h>struct Employee{

int employees;int year;float payrate;

Employee(int e, int y, float p){

employees =e;year =y;payrate =p;

}};

void main(void){

Employee emp(120, 2004, 25.55);cout << " Employees: “ << emp.employees << endl;cout << " Fiscal Year: “ << emp.year << endl;cout << "Starting Rate: “ << emp.payrate << endl;

}


Structure constructors accept arguments, too


Notes: 167


Structures as Bit FieldsStructures can be used to identify individual bit

fields

struct {unsigned field1 : 1;unsigned field2 : 1;unsigned field3 : 1;unsigned field4 : 1;

} fourbits;

struct {unsigned field1 : 1; // max value is 1unsigned field2 : 1;unsigned field3 : 3; // max value is 7unsigned field4 : 3;

} mybits;


Structures as Bit Fields

struct {unsigned first : 1;

: 2;unsigned second : 1;

: 3;unsigned third : 2;

} gaps;

Max Values for some bit fieldsBits Maximum Value1 12 33 74 155 316 63


Notes: 168


Structures as Bit FieldsPC Configuration switchesstruct equip_word {

unsigned has_drive : 1;unsigned : 1;unsigned mother_bd : 2;unsigned video_card : 2;unsigned num_drives : 2;unsigned : 1;unsigned com_cards : 3;unsigned game_port : 1;unsigned : 1;unsigned printers : 2; };


Unions (1 of 2)


union PaySource // Declare a union.{

short hours; // These two variables sharefloat sales; // the same memory space.

};


Unions variables share the same memory space

1 of 2


Notes: 169


Unions (2 of 2)void main(){

PaySource employee1; // employee1 is a PaySource union.

char hourlyType; // 'y' if hourly, 'n' if on commissionfloat payRate, grossPay;

cout << fixed << showpoint << setprecision(2);cout << "This program calculates either hourly wages or sales commission.\n";cout << "Is this an hourly employee (y or n)? ";cin >> hourlyType;

if (hourlyType == 'y') // This is an hourly employee.{

cout << "What is the hourly pay rate? ";cin >> payRate;cout << "How many hours were worked? ";cin >> employee1.hours;grossPay = employee1.hours * payRate;cout << "Gross pay: $" << grossPay << endl;

}else // Employee works on commission.{

cout << "What are the total sales for this employee? ";cin >> employee1.sales;grossPay = employee1.sales * 0.10;cout << "Gross pay: $" << grossPay << endl;

}}


Shares the same memory space


Encapsulation & Data Hiding

When you add a resistor to an existing circuit, you pick a pre-manufactured component.When you build a new garage, you use pre-configured lumber. (2x4, 2x8, etc)When you add a function to a C++ program you use pre-existing functions.The Property of a self-contained program unit is called encapsulation.Using the encapsulated unit without regard to how it works is referred to as data hiding


Notes: 170


Inheritance & Reuse

When engineers build a new car they reuse many componentsThey modify an existing modelIn C++ a new data type can be declared which is an extension of an existing data typeThis done through the use of inheritance


Classes

Classes hold member functions as well as variables

Syntax

class class_name{public:

member specification-1member specification-2member specification-3member specification-n

private:member specification-n+1member specification-n+2member specification-n+3member specification-n+4

};


Notes: 171


Classes

Classes hold member functions as well as variablesclass class_name{public:

member specification-1member specification-2member specification-3member specification-n

private:member specification-n+1member specification-n+2member specification-n+3member specification-n+4

};

int main(void){

class_name object_name;}

Once a class is defined, an object is created. An object

is similar to a variable of the class type


ClassesClasses hold member functions as well as variables#include <iostream>using namespace std;

class DayOfYear{public: // Public members

void output(); // member function prototypeint month;int day;int year;

private:float cost;

};

DayOfYear today, birthday; // Declare abstract variablesint main(void){

cin >> today.month;cin >> today.day;cin >> today.year;today.output();

}

void DayOfYear::output() // Member Function{

cout << month << "/" << day << "/" << year << cost << endl;}


Scope Resolution Operator


Notes: 172


Classes#include <iostream>using namespace std;

class DayOfYear{public: // Public members

void output(); // member function prototypeint month; // variablesint day;int year;

private:float cost; // Can only be used in member functions

};

DayOfYear today, birthday; // Declare abstract variablesvoid main(void){

cin >> today.month;cin >> today.day;cin >> today.year;// cin >> cost; // Error since cost is private

cin >> birthday.month;cin >> birthday.day;cin >> birthday.year;

today.output();birthday.output();

}


cout << month << "/" << day << "/" << year << endl;cout << cost << endl;

}


Classes hold member functions as well as variables


Classesclass DayOfYear{public:

void output(); // member function prototypevoid get_dates(); // member function prototypeint month;int day;int year;

private:int birth_year;

};


today.get_dates(); // Load todaytoday.output(); // Dump todaybirthday.get_dates(); // Load birthdaybirthday.output(); // Dump birthday

}

void DayOfYear::get_dates() // Member Function{

cout << "Enter a numeric month:";cin >> month;cout << " Enter a numeric day:";cin >> day;cout << " Enter a numeric Year:";cin >> year;

}


cout << month << "/" << day << "/" << year << endl;cout << birth_year << endl << endl;

}

Private Members


Birth_year can be accessed because it is used within the member function


Notes: 173


ConstructorsUsed to initialize classesMust be in the public section of the classCannot return a value (Must be void)Must have same name as class

class BankAccount{public:

BankAccount(int dollars, int cents, double rate);BankAccount(int dollars, double rate);BankAccount(); // default constructorvoidoutput(ostream&, outs);

private:double balance;double interest_rate;

};


Constructors

int main(void){

BankAccount account1(100, 2.3); // Call the constructorBankAccount account2; // Call default constructorBankAccount account3(500, 99, 6.6); // Call a constructor

account3 = BankAccount(999, 99, 5.5);account1 = BankAccount(1000, 7.6);

}


Notes: 174


Constructors

BankAccount::BankAccount(int dollars, int cents, double rate){

balance = dollars + 0.01 * cents;interest_rate = rate;

}

BankAccount::BankAccount(int dollars, int rate){

balance = dollars;interest_rate = rate;

}

BankAccount::BankAccount() // Default Constructor{

balance = 0;interest_rate = 0.0;

}


Another Class Example (1 of 3)

#include<iostream>#include<iomanip>

#include<math.h>using namespace std;

class mathClass{

public:mathClass();void add();void subtract();void multiply ();void divide();

void getInput();private:

double num1,num2,result;};


Notes: 175


Another Class Example (2 of 3)mathClass::mathClass(){

num1=0.0;num2=0.0;result=0.0;

}

void mathClass::getInput(){

cout << "Jim's Math Machine.......\n\n";cout << " Enter the first number: ";cin >> num1;cout << "Enter the second number: ";cin >> num2;

}

void mathClass::add(){

result=num1+num2;cout<<"The sum of the numbers is: "<<result<< endl;

}


Another Class Example (3 of 3)

void mathClass::multiply()

{result=num1*num2;cout<<"The Product of the numbers is: " <<result<< endl;

}

void mathClass::subtract()

{result=num1-num2;cout<<"The Difference between the numbers is: "<<result<< endl;

}

void mathClass::divide()

{result=num1/num2;cout<<"The quotient of the numbers is: "<<result<< endl;

}


Notes: 176


Wrapper Class Example

#include <iostream>#include <C:/progs/cpp/cis162/2005/mathClass.h>using namespace std;

void main(){

mathClass math;math.getInput();math.add();math.subtract();math.multiply();math.divide();

}


Review Questions#include <iostream>using namespace std;

structure book {char title[30];char author[25];int quantity;float cost;};

void main(void){book library; // Structure Variable

cout << " Enter Book Title:";cin >> library.title;cout << "Enter Authors Name:";cin >> library.author;cout << " Enter Recent Cost:";cin >> library.cost;

cout << library.title << " "; cout << library.author << " "; cout << library.cost << endl;

}

Find the error in the following structure


Notes: 177


Review Questions#include <iostream>using namespace std;

class DayOfYear{public:

void output(); // member function prototypevoid get_dates(); // member function prototypeint month;int day;int year;

private:int birth_year;

};


today.get_dates(); // Load todaytoday.output(); // Dump todaybirthday.get_dates(); // Load birthdaybirthday.output(); // Dump birthdaycin >> today.birth_year;

}

void DayOfYear::get_dates() // Member Function{

cout << "Enter a numeric month:";cin >> month;cout << " Enter a numeric day:";cin >> day;cout << " Enter a numeric Year:";cin >> year;birth_year = year-40;

}


cout << month << "/" << day << "/" << year << endl;cout << birth_year << endl << endl;

}

Find the error in the following class




Notes: 178


Chapter 7 Summary

Classes & Data Structures

ClassesConstructorsStructuresInitializing StructuresPassing Structures as Arguments


Chapter 8

Arrays, Single and Multidimensional

Single Dimension ArraysMulti Dimension ArraysDynamic Arrays


Notes: 179


Arrays

An array is used to process a collection of data with the same data type.

ExamplesList of test scores or temperaturesList of names or addresses


Arrays

Scalar Variablesint count;int day;float cost;char letter;

Arraysint days[6];

1234

31

34.55

W

Each variable of a scalar takes one location

0th 1st 2nd 3rd 4th 5th 6th

123 322 332 455 122 32 432


Notes: 180


Arrays

Declaring an Array#define SIZE 100char name[25];int counts[1000];double prices[90];int quan[SIZE];int table[5][5];char matrix[10][20];unsigned short int mat[6][5];


Arrays

Declaring an Arrayint score[5];

Same As:int score1;int score2; int score3; int score4; int score5;

Like declaring 5 different, but similar variables.

Arrays work very well when trying to do 1000’s of declarations


Notes: 181


Internally, looks like this . . . .

0080 00000000 score[0]0081 000000000082 00000000 score[1]0083 000000000084 00000000 score[2]0085 000000000086 00000000 score[3]0087 000000000088 00000000 score[4]0089 00000000008A 00000000008B 00000000008C 00000000008D 00000000

Assuming a 2-byte integer. Some machines

now use 4 bytes for integers.


Common Error

Declaring an Arrayint score[5];

score[5]; // index out of bounds

index = 12;score[index];


Notes: 182


Common Errorint counts[5] = {2,4,6,8,10};int i = 1000;

for (i=0; i<=5; i++)counts[i]=0;

0th 1st 2nd 3rd 4th i variable

0 0 0 0 0 0 0

0th 1st 2nd 3rd 4th i variable

2 4 6 8 10 1000 0Before �

After �

Trouble Here


Arrays

#include <iostream>#include <iomanip>#include <string>#define MONTHS 12


void main(){

string month[]={"January", "February", "March", "April", "May", "June", "July", "August“, September", "October", "November", "December"};

int days[]={31,28,31,30,31,30,31,31,30,31,30,31};int i;

for (i=0; i<MONTHS; i++){cout << setw(16) << left << month[i] << " has ";cout << setw(4) << right << days[i] << " days.\n";}

}

January has 31 days.February has 28 days.March has 31 days.April has 30 days.May has 31 days.June has 30 days.July has 31 days.August has 31 days.September has 30 days.October has 31 days.November has 30 days.December has 31 days.


Notes: 183


Arrays

#include <iostream>#include <iomanip>#include <string>#define MONTHS 12


void main(){

string month[]= {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};

int days[]={31,28,31,30,31,30,31,31,30,31,30,31};int month_input;

cout << "Enter the Month to Print(1-12): ";cin >> month_input;

month_input--;cout << "You requested " << month[month_input] << endl << endl;

}

Enter the Month to Print(1-12): 2You requested February


Arrays

100 101 102 103 104 105 106 107 108 109

#include <iostream> // for cout#include <iomanip> // for setw

void main(){int numbers[10];int i, x;i = 0;x = 100;

for (i=0; i<10; i++)numbers[i]=x++;

for (i=0; i<10; i++)cout << i << setw(5) << numbers[i] << endl;

}

0 1001 1012 1023 1034 1045 1056 1067 1078 1089 109


Notes: 184


Array Initialization#include <iostream>using namespace std;

void main(){

int children[3] = {2, 12, 3};char codes[4] = {'A', 'C', 'Z', '$'};long vectors[] = {12, 23, 43, 54, 2, 99, 21};

int n;int size;

// calculate the size of the vectors arraysize = sizeof(vectors) / sizeof(long);for (n=0; n<size; n++)

vectors[n]=0;

cout << sizeof(vectors) << endl;cout << sizeof(long) << endl;cout << size << endl;}

Also, can be read in from a disk file



Initializing Arrays

Initializing a one dimensional array of integersint testscores[10] = {98,87,88,89,90,100,76,99,91,81};

Initializing a two dimensional array of integersint matrix[2][3] = {

{43,54,65},{44,65,99}}

int matrix[2][3] = {{43,54,65},{44,65,99}}


Notes: 185


Initializing Arrays

You initialize this array by writingint theArray[5][3] = { 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15 }

For the sake of clarity, you could group the initializations with braces. For example,

int theArray[5][3] = { {1,2,3}, {4,5,6}, {7,8,9}, {10,11,12}, {13,14,15} };


Common Error

Indexes always start at zero in C or C++Called, zero relativeMost languages start at 1 (COBOL, VB, FORTRAN)

Fence Post ErrorsIt is so common to write to one past the end of an array that this bug has its own name. It is called a fence post error. This refers to the problem in counting how many fence posts you need for a 10-foot fence if you need one post for every foot. Most people answer 10, but of course you need 11. (Excerpt from C++ in 21 days)


Notes: 186


Coding Practice

Use the const to make the size of the array

#include <iostream>const int MAX_PEOPLE = 20;

main(void){int array_employee_numbers[MAX_PEOPLE];int n=0;for (n=0; n<MAX_PEOPLE; n++)

array_employee_numbers[n]=0;

}Code verified 11/17/2001


Passing Arrays by Reference#include <iostream>#define SIZE 10

void dump_array(int ar[], int n);int test_scores[SIZE] = {98,87,88,89,90,100,76,99,91,81};

int main(void){

dump_array(test_scores, SIZE);cout << "2 is " << test_scores[2] << endl;return(0);

}

// Pass the address of the array and the sizevoid dump_array(int ar[], int n){int i;for (i=0; i<n; i++)

cout << "Score " << i << " is " << ar[i] << endl;ar[2]=200; // modify element 2}

Generated OutputScore 0 is 98Score 1 is 87Score 2 is 88Score 3 is 89Score 4 is 90Score 5 is 100Score 6 is 76Score 7 is 99Score 8 is 91Score 9 is 812 is 200



Notes: 187


How Much Space Does an Array Take?

If you declared an array of 100 floats you would get 400 bytes of contiguous memory allocated to the array. For example:

float array1[100];

Each element, (sometimes called buckets) of the array takes fourbytes because of the floating point space needed for one variable. The compiler gives us 100 of these so 100 elements times 4 bytes each gives 400 bytes internally for the array. This same principle can be applied to integer, double, characterand long. Be careful of type struct, though. There are some filler and padding that takes place that is not visible to the programming eye.


Arrays and Structures#include <iostream>struct windinfo{

double velocity;char direction;long temperature;

};

void main(){windinfo weather[100]; // Array of 100 windinfoint x;

// initialize the structure membersfor (x=0; x<100; x++){

weather[x].velocity = 0;weather[x].direction = 'S';weather[x].temperature = 0;

}

cout << "Let's print out some sizes“ << endl;cout << " Windinfo:" << sizeof(windinfo) << endl;cout << " Weather:" << sizeof(weather) << endl;cout << " Velocity:" << sizeof(double) << endl;cout << " Direction:" << sizeof(char) << endl;cout << "Temperature:" << sizeof(long) << endl;

}

Let's print out some sizesWindinfo:16Weather:1600

Velocity:8Direction:1

Temperature:4



Notes: 188


Multidimensional Arrays

char page[30][100];

This array has two indexesThe first is from 0 to 29the second is from 0 to 99page[0][0], page[0][1] … page[0][99]page[1][0], page[1][1] … page[1][99]page[2][0], page[2][1] … page[2][99]

page[29][0], page[29][1] … page[29][99]


Arrays of Strings

char names[45][100];char addresses[45][100];

These arrays have two indexesThe first is from 0 to 44, the second is from 0 to

99names array holds data like:

SmithLeonardWilsonDotolo


Notes: 189


Dynamic Arrays#include <iostream>using namespace std;

typedef int* Integer_Array;

void main(void){int array_size=0;int i=0;

cout << "Enter array size:";cin >> array_size;Integer_Array arr;arr = new int[array_size];

for (i=0; i<array_size; i++)arr[i]=i;

for (i=0; i<array_size; i++)cout << arr[i] << endl;

delete [] arr;} Code verified 11/17/2001


Review Questions1. Arrays in C++ start at the __________ element?2. Arrays of characters are sometimes called _____?3. What is a common error when using arrays?4. Find the errors in the following array declarations.

1. int array1(1000);2. char name{45};3. float costs[ ] = 12.99, 23.45, 45.12;

5. Find the errors in the following array statements.1. array1[1001]=100;2. name[-1]=‘a’;3. costs(1)=12.98;

This section corresponds to Chapter 8 in the Text by Tony Gaddis, Starting Out With C++, 4th Edition


Notes: 190




Chapter 8 Summary

Arrays Summary

Single DimensionMulti DimensionStatic and Dynamic


Notes: 191


Chapter 9 – Sorting & Searching

Sorting Searching Concepts

Exchange SortSelection SortMerge SortQuick SortBinary Search


Sorting an Array

Many types of sorting algorithmsHashInsertionBubble (Exchange)SelectionShellTournamentShaker Quick SortMerge SortPoly-PhaseCascadeOscillatingCrisscross

Sorting and Sort Systemsby Harold Lorin.


Notes: 192


Clocking a C++ Program The header file time.h includes definitions for: 1. a type clock_t, which is some integer type; 2. a function clock_t clock(), which returns the elapsed time since

its first call in some unit; and 3. a constant CLOCKS_PER_SEC, which gives the number of time

units (as returned by clock()) in one second. In order to use the clock() function, a C or C++ program must

contain:

#include <time.h>clock_t tv1, tv2;double time;tv1 = clock();

// insert code to time here

tv2 = clock();time = (tv2 - tv1)/(CLOCKS_PER_SEC / (double) 1000.0);

In the above code, we compute time as a double in case CLOCKS_PER_SEC is less than 1000


Bubble Sort (Exchange Sort)

Bubble Sort Algorithm1. Compare element-0 with

element-12. If element-0 is greater than

element-1, then swap the two elements

3. Continue on with element-1 and element-2

4. Continue on with element-2 and element-3

5. Elements are known as element n and element n+1

6. Continue until the end of the array is reached

7. Repeat steps 1 through 6 until no swaps are made

8. This algorithm is known as an n2 algorithm

9. On an array of 10 it could take as many as 100 swaps


Notes: 193


Bubble Sort (Exchange Sort)

Bubble Sort Algorithm Discussion

1. There are ways to “speed up” the bubble sort

2. Inside the inner loop, test to see if you swapped anything

3. If no swaps were made the sort is finished. This will usually cut the sort time in half unless the data is reversed from the start

4. Bubble sort is an n2algorithm

5. Methods1. Swap2. Needs two loops, inner and

outer


Bubble Sort (1 of 3)#include <iostream>#include <time.h>using namespace std;

void initialize_array(void);int sort_it(int a[]);

const int SIZE = 10000;int main_array[SIZE];

void main(){

int swaps;clock_t tv1, tv2;double time;

initialize_array();tv1 = clock();swaps=sort_it(main_array);tv2 = clock();time = (tv2 - tv1)/(CLOCKS_PER_SEC / (double) 1000.0);

cout << "Swaps:" << swaps << endl;cout << "Time:" << time << " milliseconds" << endl;

} // end of main

Know as the n-squared methodAlso known as the exchange sort.


Notes: 194


Bubble Sort (2 of 3)// sort the arrayint sort_it(int arr[]){int x, swap;int swaps=0;bool we_swapped_one=false;

// do the sortdo{

we_swapped_one=false;for (x=0; x<SIZE-1; x++){if (arr[x]>arr[x+1])

{swap=arr[x];arr[x]=arr[x+1];arr[x+1]=swap;swaps++;we_swapped_one=true;

}} // end of inner for loop

}while (we_swapped_one);return(swaps);} // end of function sort_it

Know as the n-squared methodAlso known as the exchange sort.


Bubble Sort (3 of 3)

// Initialize the array with random numbersvoid initialize_array(){

int number;

for (int i=0; i<SIZE; i++){number=rand();number = number % 10000;main_array[i]=number;}

}


Notes: 195


Shaker SortShaker Sort Algorithm Discussion1. A Shaker Sort is bi-directional bubble sort

because we work from both ends2. Alternate movements between 0 and n on one

pass to n and 0 on the next pass. This will move an element right to the top or bottom depending on which way you are moving.

3. It gets its name because of the way it moves about the list, back and forth like a salt shaker or the popular beverage mixer.

4. http://users.net1plus.com/brianl/ShakerSort.htm


Selection Sort

Selection Sort Algorithm

1. Starting at the 0th element, search for the smallest element in the set 0 through n. Exchange with the 0th element

2. Starting at element-1, search for the smallest element in the range 1 through n. When found, exchange with element-1

3. Starting at element-2, search for the smallest in 2 through n. Exchange with the 2nd element

4. Starting at element-3, search for the smallest in 3 through n. Exchange with the 3rd element

5. Continue until the nth element is reached

0 1 2 3 4


Notes: 196


Selection Sort

Algorithm

1. Find the smallest element in the set 0-n

2. Exchange with the zero element3. Find the smallest in 1-n4. Exchange with the 1st element5. Find the smallest in 2-n6. Exchange with the 2nd element7. Find the smallest in 3-n8. Exchange with the 3rd element9. Continue until the n-th element

is reached


Selection Sort

Selection Sort DiscussionMethods

1. Search for the lowest element starting from nth element2. Swap the lowest element with nth element

The insertion sort is considered to be an n2 algorithm

10 20 30 40 50 60 70 80 90 100N (thousands)

180

150

120

90

60

30

0


Notes: 197


Selection Sort Code (1 of 3)#include <iostream>#include <time.h>using namespace std;

void initialize_array(void);int sort_it(int a[]);


void main(){

int swaps;clock_t tv1, tv2;double time;

initialize_array();tv1 = clock();swaps=sort_it(main_array);tv2 = clock();time = (tv2 - tv1)/(CLOCKS_PER_SEC / (double) 1000.0);

cout << "Swaps:" << swaps << endl;cout << "Time:" << time << " milliseconds" << endl;

} // end of main


Selection Sort Code (2 of 3)// Function to Perform the Selection Sortint sort_it(int array[]){

int startScan, minIndex, minValue, swaps=0;

for (startScan = 0; startScan < (SIZE - 1); startScan++){

minIndex = startScan;minValue = array[startScan];for(int index = startScan + 1; index < SIZE; index++){

if (array[index] < minValue){

minValue = array[index];minIndex = index;swaps++;

}}array[minIndex] = array[startScan];array[startScan] = minValue;

}return(swaps);

}


Notes: 198


Selection Sort Code (3 of 3)

// Initialize the array with random numbers

void initialize_array(){

int number;

for (int i=0; i<SIZE; i++){

number=rand();number = number % 10000;main_array[i]=number;}

}


Sort Animation Web SiteDemonstration of Selection, Bubble, Insertion,

Heap, Merge and Quick Sorts

http://www.ship.edu/~cawell/Sorting/selintro.htm


Notes: 199


Searching an Array

Picture a phonebook How would you find a number by name?

Search alphabeticallyHow would you find a name by using a number?

Search linearlyLinear Search

Start at the beginning and test every occurrence

Binary SearchSort the dataSuccessive slicing in half


Searching an Array Sequentially

Sequential Search#include <string.h>#include <iostream>using namespace std;int k, size;int a[]={32,43,54,65,90,21,23,34,45,65, 67,879, 89, 200,

33, 41, 34};

int main(void){

size = sizeof(a) / sizeof(int);

for (k=0; k<size; k++){

if (a[k] < 50)cout << "Hit:" << a[k] << endl;

}return(0);

}

OutputHit:32Hit:43Hit:21Hit:23Hit:34Hit:45


Notes: 200


Binary SearchSay we have 100 million phone numbersSort the numbersIf we are looking for 555-480-9400To see how many tests we need we need to use logarithms

Searches = log2x, where x is the total number of itemsSearches = log2100000000 for example

How to solve:Searches = Log10100000000 / Log102Searches = 8 / 0.301029996Searches = 26.57 or rounded up to 27

From Log conversion formula (Applied Mathematics, p 1.6)logb(x) = loga(x)/loga(b)


Binary SearchFirst, Sort the dataThen, by successively cutting the array of data in half, you can narrow

down the search1. Say we are looking for 3032. See how any elements are in the array3. Choose the middle position (5 in this case)4. Compare the value at 5 (333) against the search argument (303)

204222303321324333356411444504621

Num(0)Num(1)Num(2)Num(3)Num(4)Num(5)Num(6)Num(7)Num(8)Num(9)Num(10)

Middle Position


Notes: 201


Binary Search Example ( 1 of 4)int binarySearch(int [], int, int);void initialize_array(void);int sort_it(int a[]);


void main(){

int results, empID=1, swaps;

initialize_array();swaps=sort_it(main_array);cout << "Swaps:" << swaps << endl;

while( empID != 0){

cout << "Enter the employee ID you wish to search for: ";cin >> empID;results = binarySearch(main_array, SIZE, empID);if (results == -1)

cout << "That number does not exist in the array.\n";else{

cout << "That ID is found at element " << results;cout << " in the array.\n";

}} // end of while loop

} // end of main


Binary Search Example ( 2 of 4)// Binary Search Functionint binarySearch(int array[], int num, int value){

int last = num - 1;int first = 0; int middle;int position = -1; bool found = false;

while (!found && first <= last){

middle = (first + last) / 2; // Calculate midpoint

if (array[middle] == value) // If value is found at midpoint{

found = true;position = middle;

}else if (array[middle] > value) // If value is in lower half

last = middle - 1;else

first = middle + 1; // If value is in upper half}

return position;}


Notes: 202


Binary Search Example ( 3 of 4)

// Initialize the array with random numbersvoid initialize_array(){

int number;

for (int i=0; i<SIZE; i++){number=rand();number = number % 10000;cout << number << endl;main_array[i]=number;}

}


Binary Search Example ( 4 of 4)// sort the arrayint sort_it(int arr[]){

int x, swap;int swaps=0;bool we_swapped_one=false;

// do the sortdo{

we_swapped_one=false;for (x=0; x<SIZE-1; x++){if (arr[x]>arr[x+1])

{swap=arr[x];arr[x]=arr[x+1];arr[x+1]=swap;swaps++;we_swapped_one=true;

}} // end of inner for loop

}while (we_swapped_one);return(swaps);

} // end of function sort_it


Notes: 203


Indexed Files and SQL Indexes

1. An Indexed File has two, or more, parts2. Data is kept in the Data Part in Birth Order3. A separate file of keys is maintained for each key field (index field)4. Sometimes there can be several key files

Data Part


Chapter 9 Summary

Sorting and Searching

Bubble SortsSelection SortsBinary Search


Notes: 204


Chapter 10 – C++ Strings

Character Arrays & String Class

StringsCharacter ArraysString FunctionsString Class


String Basics

A String Literal: cout << “Hello”

A cstring variable: char book_title[30];

Null Character, \0Also known as low-values


Notes: 205


String Function Previewgets() puts()strcat() strcpy()strcmp() strstr()isalnum() isalpha()iscntrl() isdigit()isgraph() strupr()islower() isprint()ispunct() isspace()isupper() isxdigit()toupper() tolower()memset() memcpy()ctype.h string.h


String Data

#include <iostream> using namespace std;char name[40]; // 40 characterschar address[50]; // 50 characterschar state[3];

int main(void){

state[0]=‘A’;state[1]=‘Z’;state[2]=0;strcpy(name, ”Will Smith ”);strcpy(address, “1234 W. Pecos ”);cout << name << address << state << endl;

}

0 is same as null is same as ‘\0’

Strings in C++ are no more than an array of characters.


Notes: 206


String Data Using C++#include <iostream>using namespace std;

void main(){

char sentence[] = "Hello World";int count = 0;

for (int i = 0; sentence[i] != '\0'; i++){

count++;}

cout << "The string " << sentence << " has " << count<< " characters and is stored in " << count+1 << " bytes\n";

}0 is same as null is same as ‘\0’Output:The string Hello World has 11 characters and is stored in 12 bytes

Strings in C++ are no more than an array of characters.


Strings in C++

char name[20] = “SMITH “;

terminated with low-values or binary zero \0called ASCIIZ strings

ASCII Data Followed by a Binary Zerostring functions will insert appropriate \0 (NULL)if you are building your own strings, you must insert \0strings are zero relative

Example:name[5]=‘\0’; // optionally name[5]=0;

cout << name << endl’


Notes: 207


Strings in C++

Examples of string declarations

char name[20] = “SMITH \0“;char address[30];char zip_code[5];char input_area[1000];Computer Memory is sequential and linear

C I S 1 6 2 \0


Difference Between \0 and “0”Binary Zero 00000000 NULL or \0ASCII Zero 00110000 48 or Character Zero

0 48 001100001 49 001100012 50 001100103 51 001100114 52 001101005 53 001101016 54 001101107 55 001101118 56 00111000


Notes: 208


ASCII v. Numeric


void main(){

int counter;

for (counter=32; counter<255; counter++){

cout.width(1);cout << (char) counter;cout.width(4);cout << counter << endl;

}}


32! 33" 34# 35$ 36% 37& 38' 39( 40) 41* 42+ 43, 44- 45. 46/ 470 481 492 503 514 525 536 547 55


ASCII v. Numeric


Notes: 209


String or Character

char ch;

ch = ‘A’; // character A stored in memorych = “A”; // character A followed by \0

ch = A; // loads ch with the variable A

ASCIIAmerican Standard Code for Information Interchange


String Literals

A set of characters“string literal” wrapped on double quotes

Characters wrapped in single quotesStrings wrapped in double quotes

Also called a character arrayMax length ANSI, is 509 bytesMax length, Microsoft, is 2008 bytesAlways end with NULL (Binary Zero, \0)

cout << “This is a string literal..”;char msg1[]=“This is a C string literal”;


Notes: 210


strcpy() -- Assigning a Value to a String

char msg1[]=“This is a C++ string”;char msg2[]=“Also Called Character Arrays”;

Or

strcpy(msg1, “This is a C++ string”);strcpy(msg1, msg2);

C++ Prototypechar strcpy(char *str1, char *str2)

Copy contents of str2 to str1. Str2 must be a NULL-terminated string. ( ASCIIZ string )

strcpy(address, “2626 E. Pecos Rd.”);


strncpy()

prototypestrncpy(strcpy(char *str1, char *str2, int count)

Examplesstrncpy(str1, str2, count)strncpy(str1, str2, count+1)strncpy(str1, str2, 12)

Note:if str1 cannot hold the contents of str2 then behavior is undefined.


Notes: 211


strcat() – String Concatenationchar strcat(char *str1, char *str2)

Concatenates a copy of str2 onto str1. Str2 must be a NULL-terminated string. ( ASCIIZ string )

Let’s assume we have…char address_1[13]=“2626 E. Pecos”;char address_2[17]=“Gilbert, AZ 85234”;char address_3[50];

strcpy(address_3, address_1);strcat(address_3, address_2);

Address_3 Now Contains:2626 E. Pecos Rd. Gilbert, AZ 85234

str2 is untouched by the operation.No bounds checking is performed. Programmer must do this.Programmer must ensure str1 will hold str2.


strncat() – String Concatenationchar strncat(char *str1, char *str2, int count)

Concatenates a copy of str2 onto str1. Str2 must be a NULL-terminated string. ( ASCIIZ string )

Let’s assume we have…char address_1[13]=“2626 E. Pecos”;char address_2[17]=“Gilbert, AZ 85234”;char address_3[50];

strncpy(address_3, address_1, 13);strncat(address_3, address_2, 17);

Address_3 Now Contains:2626 E. Pecos Rd. Gilbert, AZ


Notes: 212


strcmp() – String ComparisonPrototypeint strcmp(char *str1, char *str2)char message[]="This is a string";// Method Oneif (strcmp(message, "This is a string"))

cout << "Strings are NOT the same\n";else

cout << "Strings are the same\n";

// Method Twoif (strcmp(message, "This is a string") == 0)

cout << "Strings are the same\n";else

cout << "Strings are NOT the same\n";

// Method Threeif (! strcmp(message, "This is a string"))



Returns< 0: str1 is less than str2= 0: str1 = str2> 0: str1 is greater than str2


strncmp() – String ComparisonPrototypeint strncmp ( const char * string1, const char * string2, int num );char message[]="This is a string";// Method 1if (strncmp(message, "This is", 7))

cout << "Strings are NOT the same\n";else

cout << "Strings are the same\n";

// Method 2if (strncmp(message, "This is a", 9) == 0)



// Method 3if (! strncmp(message, "This", 4))



Returns< 0: str1 is less than str2= 0: str1 = str2> 0: str1 is greater than str2


Notes: 213


Common Error

A common error in C++ programming is to attempt to set a variable to a string literal using the assignment operator.

This is Illegal with Character Arraysmessage = “This is a string”;

Proper method:strcpy(message, “This is a string”);strcpy(message, myString);

Assume:char message[40]=“Test String One”;char myString[40]=“My String Data”;


Common Error

A common error in C++ programming is to attempt to compare string variables using the if command.

This is Illegal:if (message == “This is a string”)

do_something;

Proper method:if (strcmp(message, “This is a string”))

cout << “Strings are NOT the same”;else

cout << “Strings are the same”;

< 0: str1 is less than str2= 0: str1 = str2> 0: str1 is greater than str2


Notes: 214


strlen() function

char name[25] = “Ada Lovelace”;int x;x = strlen(name);

x should contain the number of characters in name.

Remember:sizeof() shows the length of the variable spacestrlen() shows the actual length of the string contents

Ada Lovelace Born: London, England, December 10, 1815 Died: London, England, November 27, 1852 Analyst, Metaphysician, and Founder of Scientific Computing


Application

One use for strlen()To test for an empty input string. Examples:

int x;cin >> name;x = strlen(name);if (x == 0)

{cout << “Invalid Named Entered \n”;}

or

if (strlen(name) == 0){cout << “Invalid Named Entered \n”;}


Notes: 215


getchar()reads a character from the keyboard

#define LF 10int count;char name[30];

int main(void){

count=0;while (count < 30){name[count] = getchar();if (name[count] == LF){name[count]=0;break;}

count++;}

cout << name << endl;}


putchar()writes a character to the screen (stream I/O)#include <iostream.h> // for cout#include <stdio.h> // for putchar#include <string.h> // for strlen

int x, length;char name[30]="Samira Munoz\0";

void main(void){

x=0;length=strlen(name);

// Write the name oncewhile (x < length)

{putchar(name[x]);x++;}

// Write the name againcout << endl << name << endl;}



Notes: 216


getchar() & putchar() Combo

#include <stdio.h> // for putchar & getchar

char ch;void main(void){

while ((ch = getchar()) != EOF)putchar(ch);

}

This is only a test[ENTER]This is only a test

EOF is typically -1 when reading data filesCTRL-Z for PC keyboard inputCTRL-D for Unix keyboard input



puts() and gets()

Quick and dirty way to obtain text from keyboard and print text to the screen.

puts(stringvar);puts(“Literal”);gets(stringvar);


Notes: 217


toupper() and tolower()int toupper(int ch) // prototypeint tolower(int ch) // prototype

Returns the uppercase equivalent of ch if ch is a letter otherwise ch remains unchanged.

char ch;ch = ‘w’;ch = toupper(ch);cout << ch;

Returns the lowercase equivalent of ch if ch is a letter otherwise ch remains unchanged.

char ch;ch = ‘Q’;ch = tolower(ch);cout << ch;


Getline Member Function

Member function to read a line of inputSyntax:input_stream.getline (string_var, Max_Characters + 1);

Examples:char st[30];

cin.getline(st, 30);cin.getline(st, sizeof(st));


Notes: 218


toupper() and tolower() Returns an Intint toupper(int ch) /* prototype */int tolower(int ch) /* prototype */

ch = ‘a’;cout << toupper(ch); // Prints 65

ch = ‘a’;cout << tolower(ch); // Prints 97

Why ?toupper and tolower return integer results

Be Careful when embedding these functions in the cout object


toupper() and tolower()int toupper(int ch) /* prototype */int tolower(int ch) /* prototype */

ch = ‘a’;cout << (char) toupper(ch); // Prints A

ch = ‘A’;cout << (char) tolower(ch); // Prints a

// Less confusing way. . .ch = ‘A’;ch = tolower(ch);cout << ch; // Prints a


Notes: 219


islower() and isupper()int islower(int ch)

Returns nonzero value if ch is a lower case letter(a-z), otherwise returns zero.

char ch;ch = getchar();if (islower(ch))

puts(“Lowercase Letter Found”);

int isupper(int ch)

Returns nonzero value if ch is an upper case letter(A-Z), otherwise it returns zero.

char ch;ch = getchar();if (isupper(ch))

puts(“Uppercase Letter Found”);


isalnum() & isalpha()

int isalnum(int ch) /* Alphanumeric Test */Returns non-zero value if its argument is either a letter or a digit.

Non-zero means true.char ch;ch = getchar();if (isalnum(ch))

cout << “Alphanumeric Character Found”;

int isalpha(int ch) /* Alphabetic Test */Returns non-zero value if its argument is a letter.char ch;ch = getchar();if (isalpha(ch))

cout << “Alphabetic Character Found”;


Notes: 220


ispunct() & isspace()int ispunct(int ch) // Punctuation Test// Returns non-zero value if ch is a punctuation character.

!@#$%^&*()_-+= etc

char ch;ch = getchar();if (ispunct(ch))

cout << “Punctuation Character Found”;

int isspace(int ch) // Space Test// Returns non-zero value if ch is a space character( hex

20).

char ch;ch = getchar();if (isspace(ch))

cout << “We have a Space Character”;


isxdigit() & isascii()

int isxdigit(int ch) // Hex Digit Test // Returns non-zero value if ch is A-F, a-f or 0-9.

char ch;ch = getchar();if (isxdigit(ch))

cout << “Hex Digit Encountered”;

int isascii(int ch) // ASCII Char Test// Returns non-zero value if ch is between 0 and hex 7F, otherwise returns 0.char ch;ch = getchar();if (isascii(ch))

cout << “ASCII Character Encountered”;


Notes: 221


iscntrl() & isdigit()

int iscntrl(int ch) /* Control Char Test */

Returns non-zero value if ch is between 0 and hex 1F or hex 7F (DEL), otherwise returns 0.

char ch;ch = getchar();if (iscntrl(ch))

cout << “Control Character Found”;

int isdigit(int ch) /* Digit Test */

Returns non-zero value if ch is a digit, otherwise returns a zero.

char ch;ch = getchar();if (isdigit(ch))

cout << “We have a Number”;


atoi(), atol(), atof(), itoa()

ASCII to Integer Conversion Function.Takes in a string argument and returns its integer

equivalent

Syntax:int atoi(string_var);

Example:void main(){

int x=0;char st[7]="654321";x = atoi(st);cout << "Length of String: " << sizeof(st) << endl;cout << "Length of x: " << sizeof(x) << endl;

}

Length of String: 7Length of x: 4

Also: atol & atofPronounced:

A to I, A to L, A to F

itoa for integer to ASCII


Notes: 222


atoi(), atol(), atof() #include <iostream.h> // for cout#include <stdlib.h> // for atoi, etc

int x;float y;long z;

char int_st[12];char float_st[12];char long_st[12];

void main(void){

cout << "Enter some numbers" << endl;cin >> int_st;cin >> float_st;cin >> long_st;

x=atoi(int_st);y=atof(float_st);z=atol(long_st);

x*=2;y*=2;z*=2;

cout << x << endl;cout << y << endl;cout << z << endl;

}



strupr()

char strupr(char *str) // prototype

Converts the string pointed to by str to uppercase.

char name[20]=“Charles Babbage\0”;int main(void){

strupr(name);cout << name << endl;

}

printsCHARLES BABBAGE


Notes: 223


strlwr()

char strlwr(char *str) // prototype

Converts the string pointed to by str to lowercase.

char name[20]=“Charles Babbage\0”;int main(void){

strlwr(name);cout << name << endl;

}

printscharles babbage


Let’s See What We Know…#include <stdio.h> #include <ctype.h> #include <string.h>

char fname[20];char lname[20]; char full_name[60];

void main(void){

puts("Enter your First Name");gets(fname);puts("Enter your Last Name ");gets(lname);

if (islower(fname[0]))fname[0]=toupper(fname[0]);

if (islower(lname[0]))lname[0]=toupper(lname[0]);

strcpy(full_name,fname);strcat(full_name, “ “); strcat(full_name,lname);puts(full_name);

strupr(full_name);puts(full_name);

}


Notes: 224


strstr()char strstr(char *str1, char *str2)Returns a pointer to the first occurrence in str1 of the string pointed to by

str2.

char *p;p = strstr(“This is a test”, ”te”);if (p == 0)

cout << “No Find”;


strspn Function/* STRSPN.C: This program uses strspn to determine* the length of the segment in the string "cabbage"* consisting of a's, b's, and c's. In other words,* it finds the first non-abc letter. */

#include <string.h>#include <stdio.h>

void main( void ){

char string[] = "cabbage";int result;result = strspn( string, "abc" );printf( "The portion of '%s' containing only a, b, or c "

"is %d bytes long\n", string, result );}

Generated OutputThe portion of 'cabbage' containing only a, b, or c is 5 bytes

longCourtesy MSDN Online


Notes: 225


memset() & memcpy()

void memset(void *buf, char ch, unsigned count) // Copies ch to memory area pointed to by buf, count

times.

char array[1000];memset(array, ‘ ‘, 1000);

void memcpy(void *dest, void *src, unsigned count) // Copies count characters from src to dest.

char array[1000];char buffer[1000];memcpy(array, buffer, 1000);

Not in Book


String Class

#include <string>#include <iostream>using namespace std;

void main(void){

string first_name, last_name;first_name="Abraham";last_name="Lincoln";cout << first_name << " " << last_name << endl;cout << first_name.capacity();cout << "\n\n\n";

}



Notes: 226


String ClassMember FunctionsAtAppendAssignBeginCopyCapacityCompareEndEraseFindInsertLengthReplaceSizeSwapSubstr


String Class#include <string>#include <iostream>using namespace std;

int main(void){string first_name, last_name;string whole_name;

first_name="Allen";last_name="Shepard";whole_name=last_name;whole_name.append(", ");whole_name.append(first_name);

cout << first_name << " ";cout << first_name.length() << " ";cout << first_name.capacity() << endl;cout << whole_name << endl;

whole_name.at(7)=' '; // spaces out the commacout << whole_name << endl;

whole_name.at(7)=0; // chops off the last namecout << whole_name << endl;}

Allen 5 31

Shepard, Allen

Shepard Allen

Shepard

Generated Output


Notes: 227


String Class#include <string>#include <iostream>using namespace std;

void main(void){string first_name, last_name;string whole_name;long ptr;

first_name="Allen";last_name="Shepard";whole_name=last_name;whole_name.append(", ");

// append starting at 0, for 2 byteswhole_name.append(first_name,0,2);

// erase 1 char starting pos 2, compress the strwhole_name.erase(2,1);cout << whole_name << endl;

ptr = whole_name.find("ar");cout << ptr << endl;if (ptr > whole_name.capacity())

cout << "Cannot find selected substring\n\n";else

{whole_name.at(ptr) = 'Q';cout << whole_name << endl;}

}

Shpard, Al

3

ShpQrd, Al

Generated Output


Review Questions1. Strings in C++ are simply ___________ arrays2. A binary zero is 000000002 or 001100002

3. String Literals are wrapped with ______ quotes4. The strlen() function can be used to __________5. strcat() does what?6. strcpy does what?7. Explain isupper() 8. Explain tolower()9. Explain atoi()10. What String Class Member Function can be used to concatenate

two strings11. What String Class Member Function can be used to replace a

specific character in a string


Notes: 228


Homework1. Should have read Chapters 1 through 10 and 12 by now2. Work on your term paper3. Work on Packet-3…


Chapter 12 Summary

Everything you ever wanted to know about C++ string manipulation, but were afraid to ask.

String Class

StringsString FunctionsC++ String Class


Notes: 229


Chapter 13

Files, I/O Streams, Advanced I/O

Stream I/OCharacter I/OInheritance


C++ General I/O

Data stored in disk filesC++ used to read in and write out dataPrograms “read in” data from a file to a programPrograms “write out” data from the program to a disk fileIn other words, the I/O is program relative

C++ Program Disk File


Notes: 230


File and Record Hierarchy1. Databases contain sets of related files2. Files contain records3. Records contain fields4. Fields contain characters (bytes)5. Bytes are made up of bits6. Bits

Think of a File Cabinet (Database)Contains Drawers (Files)Contains Folders (Records)


Introduction to Files (Writing)

#include <fstream>using namespace std;

void main(void){

ofstream outstream; // output file object

outstream.open("c:/myfile.dat");outstream << "Albert Einstein\n";outstream << "Michael Faraday\n";outstream << "Alexander Graham Bell\n";outstream << "Jimi Hendrix\n";outstream << "Kurt Cobain\n";outstream.close();

}


Albert EinsteinMichael FaradayAlexander Graham BellJimi HendrixKurt Cobain


Notes: 231


Introduction to Files (Reading)

#include <iostream>#include <fstream>#include <string>using namespace std;

void main(void){

ifstream instream; // output file objectstring celebrity;

instream.open("c:/myfile.dat");getline(instream,celebrity);cout << celebrity << endl;getline(instream,celebrity);cout << celebrity << endl;getline(instream,celebrity);cout << celebrity << endl;getline(instream,celebrity);cout << celebrity << endl;instream.close();

}Code Verified 05/12/2003

Albert EinsteinMichael FaradayAlexander Graham BellJimi Hendrix


Setting up C++ Stream I/ODefining I/O Streams

#include <fstream.h>int main(void){ifstream instream;ofstream outstream;

instream.open(“c:/myfile.dat”,ios::in|ios::nocreate);instream.close();}

Stream I/O is simply record processing.It reads and writes sets, or groups, of data.


Notes: 232


Example of the fstream object#include <iostream>#include <fstream>using namespace std;

int main(){

fstream dataFile;string buffer;

dataFile.open("myfile.dat", ios::out); // Open for outputdataFile << "Now is the time for all good men" << endl

<< "to come to the aid of their country.";dataFile.close();dataFile.open("myfile.dat", ios::in); // Open for readinggetline(dataFile, buffer); // Get first linecout << buffer << endl; // Output first linegetline(dataFile, buffer); // Get second linecout << buffer << endl; // Output second linedataFile.close();

}


Copying a Portion of a File#include <fstream>#include <string>using namespace std;

void main(void){

int i;string record_in;ifstream file_in;ofstream file_out;file_in.clear(); // clears all error codesfile_in.open("C:/data/numbers.txt", ios::in);file_out.open("C:/data/Newfile.txt", ios::out);for (i=0; i<100; i++)

{file_in >> record_in;if (file_in.fail() != 0) break;file_out << record_in << endl;}

file_in.close();file_out.close();

}

Example reading a file in and writing it out.



Notes: 233


File Open Short CutInput and output to text files are handled by including the header file

"fstream.h" and by then declaring variables of type ifstream and ofstream respectively. For example, the following program reads from a file named “myFile.dat" and writes to a file named “yourFile.dat":

#include <iostream> #include <fstream.h> using namespace std;void main() { char c; ifstream infile(“myfile.dat"); ofstream outfile("yourFile.dat"); if (outfile && infile) // They will be 0 on err.

while (infile >> c) outfile << c;


C++ Stream I/OVariations on syntax

char filestring[25]=“C:/MYFILE.DAT”;char filename[45]=“D:/INV/MASTER.DAT”;ifstream file_in, filex, payroll_master;ofstream file_out, newfile, inventory_detail;

payroll_master.open(filestring, ios::in|ios::nocreate);inventory_detail.open(filename, ios::app);


Notes: 234


Mode FlagsThe open Function for Output Streams

To use an output file stream (ofstream), you must associate that stream with a specific disk file in the constructor or the open function. If you use the open function, you can reuse the same stream object with a series of files. In either case, the arguments describing the file are the same.

When you open the file associated with an output stream, you generally specify an open_mode flag. You can combine these flags, which are defined as enumerators in the ios class, with the bitwise OR ( | ) operator.

Flag Function ios::app Opens an output file for appending. ios::ate Opens an existing file (either input or output) and seeks the end. ios::in Opens an input file. Use ios::in as an open_mode for an ofstream file to prevent truncating an existing file. ios::out Opens an output file. When you use ios::out for an ofstream object without ios::app, ios::ate, or ios::in, ios::trunc is implied. ios::nocreate Opens a file only if it already exists; otherwise the operation fails. ios::noreplace Opens a file only if it does not exist; otherwise the operationfails. ios::trunc Opens a file and deletes the old file (if it already exists). ios::binary Opens a file in binary mode (default is text mode).


File Append Example#include <fstream>using namespace std;

void main(){

fstream dataFile;

dataFile.open("demofile.txt", ios::out);dataFile << "Jones\n";dataFile << "Smith\n";dataFile.close();dataFile.open("demofile.txt", ios::out|ios::app);dataFile << "Willis\n";dataFile << "Davis\n";dataFile.close();

}


Notes: 235


Dot Operator

Objects

Calling Object.Member Function (Arguments);Examples:payroll_master.open(filestring);inventory_detail.open(filename);out_stream.precision(2);File_in.get(ch);File_out.put(ch);


Other I/O Functions

Error Processing FunctionsUse these member functions to test for errors while writing to a stream:

Function Return valuebad() Returns TRUE if there is an unrecoverable error. fail() Returns TRUE if there is an unrecoverable error or an “expected”condition, such as a conversion error, or if the file is not found. Processing can often resume after a call to clear with a zero argument. good() Returns TRUE if there is no error condition (unrecoverable or otherwise) and the end-of-file flag is not set. eof() Returns TRUE on the end-of-file condition. clear() Sets the internal error state. If called with the default arguments, it clears all error bits. rdstate() Returns the current error state. For a complete description of error bits, see the Class Library Reference


Notes: 236


fail() Example#include <stdlib.h>#include <fstream>#include <iostream>#include <string>


void main(void){

int i;string data;int count=0;

ifstream payroll_file;payroll_file.clear();payroll_file.open("C:/data/cpp/cis162/spring2003/numbers.txt", ios::in);

if (payroll_file.fail() != 0){cout << "File Open Failed with Error Code: ";cout << payroll_file.fail() << "\n";cout << "Program Aborting...\n\n";exit(1);}

for (i=0; i<10000; i++){payroll_file >> data;if (payroll_file.fail() != 0)

break;count++;}

cout << count << " Records processed...\n\n";payroll_file.close();

}



good() and append Examplestring num;string data_file="c:/data/cpp/cis162/spring2003/numbers.txt";string new_file="c:/data/cpp/cis162/spring2003/newdata.dat";

void main(void){

ifstream numbers_in;ofstream numbers_out;

// Open the input filenumbers_in.open(data_file.c_str(), ios::in);if (numbers_in.good() == false)

{cout << "Error Opening input File " << data_file << " \n\n";exit(1);}

// Open the output file for appendnumbers_out.open(new_file.c_str(), ios::app);if (numbers_out.good() == false)

{cout << "Error Opening Output File " << new_file << " \n\n";exit(1);}

// Read and write the datawhile (! numbers_in.eof())

{numbers_in >> num;numbers_out << num << endl;cout << setw(8) << num << setw(3) << numbers_in.rdstate() << endl;}

// Close the filesnumbers_in.close();numbers_out.close();

}



Notes: 237


eof() Example#include <stdlib.h>#include <iomanip>#include <fstream>#include <iostream>#include <string>using namespace std;

string data;long num;

void main(void){

ifstream payroll_file;payroll_file.open("c:/data/cpp/cis162/spring2003/numbers.txt", ios::in);if (payroll_file.fail() != 0)

{cout << "File Open Failed with Error Code: ";cout << payroll_file.fail() << "\n";cout << "Program Aborting...\n\n";}

else{while (! payroll_file.eof())

{data="";payroll_file >> data;cout << setw(9) << data << endl;}

payroll_file.close();}

}



Open Modesifstream( const char* szName, int nMode = ios::in, int nProt = filebuf::openprot );

ios::in The file is opened for input (default).ios::nocreate If the file does not already exist, the function fails.ios::binary Opens the file in binary mode (the default is text mode).Note that the ios::nocreate flag is necessary if you intend to test for the file’s

existence (the usual case).

The file protection specification; defaults to the static integer filebuf::openprot that is equivalent to filebuf::sh_compat. The possible nProt values are:

filebuf::sh_compat Compatibility share mode.filebuf::sh_none Exclusive mode — no sharing.filebuf::sh_read Read sharing allowed.filebuf::sh_write Write sharing allowed.To combine the filebuf::sh_read and filebuf::sh_write modes, use the logical OR (

|| ) operator.

(Extracted from MSDN Online)


Notes: 238


Example of a Seed Readvoid main(){

//declare and initialize variableshort score = 0;short numScores = 0; //countershort totalScores = 0; //accumulatorfloat average = (float) 0.0;

//open input fileifstream inFile;inFile.open("scores.dat", ios::in | ios::nocreate);

//verify that open was successfulif (!inFile.fail()) //if open did not fail{

//read test scoreinFile >> score; // Seed Readwhile (!inFile.eof())

{

//update counter and accumulatornumScores = numScores + 1;totalScores = totalScores + score;inFile >> score;}

//close fileinFile.close();

//calculate and display average test scoreaverage = (float) totalScores / (float) numScores;cout << "Average test score: " << average << endl;

}else //open failed

cout << "Error opening file." << endl;} //end of main function


Character I/O

#include <fstream.h>

cin.get(char variable);cout.put(char variable);

out_stream.put(char variable);in_stream.get(char variable);

cin belongs to istream, NOT ifstreamcout belongs to ostream, NOT ofstream


Notes: 239


Copy and Print a C++ Source Code File#include <fstream>#include <iostream>#include <stdlib>using namespace std;char ch;void main(void){

ifstream fin;ofstream fout;

fin.open("c:/data/c_programs/cis162ab/cross_ref.c");fout.open("c:/data/c_programs/cis162ab/new.c");if (fin.fail() != 0)

{cout << "File Open Failed with Error Code: ";cout << fin.fail() << "\n";cout << "Program Aborting...\n\n";exit(1);}

while (!fin.eof()){fin.get(ch);fout.put(ch);cout.put(ch);}

fin.close();fout.close();}



The ignore() Functionfin.ignore(100, ‘\n’); Stop reading and discarding chars

from the keyboard after consuming the next 100 chars or after consuming a newline char, whichever occurs first

fin.ignore(25, ‘#’); Stop reading and discarding chars from the keyboard after consuming the next 25 chars or after consuming a # char, whichever occurs first

cin.ignore(10, ‘$’); Stop reading and discarding chars from the keyboard after consuming the next 10 chars or after consuming a $ char, whichever occurs first


Notes: 240


Example - Editing a File of Text#include <fstream>#include <iostream>#include <cstdlib>using namespace std;

const char TAB=9;

void add_plus_plus(ifstream& in_stream, ofstream& out_stream);

void main( ){

ifstream fin;ofstream fout;

fin.open("c:/data/cpp/cis162/Spring2003/demos/demoprob22.cpp");if (fin.fail( ))

{cout << "Input file opening failed.\n";exit(1);}

fout.open("c:/data/cpp/cis162/Spring2003/demos/summaryfile.txt");if (fout.fail( ))

{cout << "Output file opening failed.\n";exit(1);}

add_plus_plus(fin, fout);

fin.close( );fout.close( );

}


void add_plus_plus(ifstream& in_stream, ofstream& out_stream){

char ch;int tabs=0;int pounds=0;int semicolons=0;

in_stream.get(ch); // seed readwhile (! in_stream.eof( )){

if (ch == ';'){out_stream << ".";semicolons++;}

else{if (ch == '#')

pounds++;if (ch == TAB)

tabs++;out_stream << ch;}

in_stream.get(ch);} // end of whilecout << " Pound Signs:" << pounds << endl;cout << " Semicolons:" << semicolons << endl;cout << "Tab Characters:" << tabs << endl;

}

Example - Editing a File of Text


Notes: 241


Basic Flow When Using Files


Formatting Output

fileout.setf(ios::fixed);fileout.setf(ios::showpoint);fileout.precision(4);

Sets the precision and attributes to be used on subsequent I/O functions. More in Appendix of Handout

setf attributesios::fixed // don’t use scientific notationios::scientific // use scientific notationios::showpoint // always show a decimal pointios::showpos // show a plus on positiveios::right // right justifyios::left // left justify


Notes: 242


I/O Manipulators

Placed after the << operatordecendlfixedfflushhexoctrightscientificsetfill(ch)setprecision(n)setw(n)showpointnoshowpointshoposnoshowpos


Write Method

Using write()Syntax: oblect.write(variable, length);

#include <iostream>#include <string>using namespace std;void main () {

char One[] = "One if by land";

int fullLength = strlen(One);int length2 = strlen(One)/2;int length3 = strlen(One)/4;

cout.write(One,fullLength) << "\n";cout.write(One,length2) << "\n";cout.write(One,length3) << "\n";

}

OutputOne if by landOne ifOne


Notes: 243


Random Access Files

#include <iostream>#include <fstream>using namespace std;

int main(){

fstream file("letters.txt", ios::in);char ch;

file.seekg(5L, ios::beg);file.get(ch);cout << "Byte 5 from beginning: " << ch << endl;file.seekg(-10L, ios::end);file.get(ch);cout << "Byte 10 from end: " << ch << endl;file.seekg(3L, ios::cur);file.get(ch);cout << "Byte 3 from current: " << ch << endl;file.close();return 0;

}

seekg is Seek Get

seekp is seek Put


Random Access Files (1 of 3)

#include <iostream>#include <fstream>using namespace std;#include "reinterpret.h"

// Declare a structure for the recordstruct Info{

char name[51];int age;char address1[51];char address2[51];char phone[14];

};

// Function Prototypeslong byteNum(int);void showRec(Info);


Notes: 244



void main(){

fstream people;Info person;

people.open("people.dat", ios::in | ios::binary);if (!people){

cout << "Error opening file. Program aborting.\n";return 0;

}cout << "Here is record 1:\n";people.seekg(byteNum(1), ios::beg);people.read(addr(&person), sizeof(person));showRec(person);cout << "\nHere is record 0:\n";people.seekg(byteNum(0), ios::beg);people.read(addr(&person), sizeof(person));showRec(person);people.close();

}



long byteNum(int recNum){

return sizeof(Info) * recNum;}

void showRec(Info record){

cout << "Name: ";cout << record.name << endl;cout << "Age: ";cout << record.age << endl;cout << "Address line 1: ";cout << record.address1 << endl;cout << "Address line 2: ";cout << record.address2 << endl;cout << "Phone: ";cout << record.phone << endl;

}


Notes: 245


sprintf() .. way coolSame as printf except output is directed into a stringSyntax:sprintf(str, ”formatting string”, variables);

Examples:sprintf(title,”%15s %8s %4i\n”, header, date, page);sprintf(line,”%8s %8s %4i %c”, acct, date, quan, status);

Great for converting numeric to stringsprintf(num,”%12.2f”, double_num);


Conversion Specifiers for sprintf

%c character%d signed decimal integer%e,E floating point e-notation or E-notation%f floating point decimal notation%g,G use %f(F) or %e(E) whichever is shorter%i signed decimal integer%o unsigned octal integer%p pointer%s string%u unsigned decimal integer%x,X unsigned hex integer%% percent sign


Notes: 246


Conversion Specification Modifiers

Format: %xywhere x is a modifier or flagand y is the specification

%7.2f uses 7 bytes with 2 bytes for decimal fraction%h4i prints short values%ld long values (long int or unsigned long int)%lf designates long double floating point%-10i left justified and use 10 bytes%+7d show plus sign and use 7 bytes% 6.2f signed values displayed with leading space.%#8.0f makes decimal point print even if value is 0%010d fill area with leading zeros


sprinf can be used to convert Binary to ASCII#include <iostream>#include <string>

using namespace std;float cost;char str[10];int length1, length2;

void main (){

cost=1243.22;sprintf(str,"%6.2f", cost);cout << str << endl;;length1=sizeof(cost);length2=strlen(str);cout << "length of cost is " << length1 << endl;cout << "length of str is " << length2 << endl;

}

Verified 10/29/2002

1243.22length of cost is 4length of str is 7


Notes: 247


Strstream – Writes to Memory

#include <iostream>#include <strstream>#include <iomanip>using namespace std;

int main(){

float squares[5] = {1, 4, 9, 16, 25};

strstream outStr; //String stream object.

outStr << showpoint << fixed << setprecision(1);outStr.clear(); // I added this to clear the bufferoutStr.flush();for (int index = 0; index < 5; index++)

{outStr << setw(10) << squares[index];

}

//Print the string on the screen.cout << outStr.str();return 0;

}

Verified 11/22/2003

Generated Output:1.0 4.0 9.0 16.0 25.0


Review Questions

Name the two types of file I/O in C++?The open statement is considered to be a _____ function.ifstream is considered to be a _____________We use ifstream and ofstream to instantiate a file _______?What member function is used to determine if the previous I/O was successful?What member function is used to capture and report the end of a file condition?What must a programmer do to re-read the first line of a file?What include directive do you need to process data files?What happens to a data file when we open it for output?Why would we want to close a file that was opened for input?Why would we want to close a file that was opened for output?What is a good use for the sprintf function?


Notes: 248


Homework1. Should have read Chapters 1 through 10 , 12 13 by now2. Work on your term paper3. Work on Homework Packets


Chapter 13 Summary

I/O Streams Summary

Stream I/OCharacter I/Ofail()good()eof()sprintf()Manipulatorssetf()


Notes: 249


Additional C++ Topics

Advanced Topics

Bitwise OperatorsBit FieldsC-Style File I/O OperationsRecursionPointersI/O Redirection


Interesting FactsMost Computers, Intel, Motorola or anything elseuse binary as the internal representation

There has been some experimentation at ASU with Base 3 (1993 time frame)

n A.A. Rodriguiz - Professor in Electrical Engineering Dept

Most PC’s, typically, use hexidecimal as the next level of data representation

Some larger machine architectures use Octal

At one time there was a Hewlett Packard machine that used base 5, or Radix 5


Notes: 250


Boolean Operations

AND OperationOR OperationXOR OperationOne’s Complement OperationLeft ShiftRight Shift


Bitwise Operations

Key to success

AND means multiplyOR means add


Notes: 251


Bitwise AND Operation

00101011 4310101010 17000101010 42 Remember to multiply

Why would we want to do this ?Convert to upper or lower case

01001101 Upper case M 7701101101 Lower case m 109

01101101 Lower case m 10911011111 Mask of 223 22301001101 Result is upper case M

Of course, we could have used toupper(‘m’);


Bitwise AND Operation#include <iostream.h>#include <iomanip.h>

unsigned val=109;unsigned mask=223; // Bitwise AND Operationunsigned newval;

main(){

newval = val & mask;cout << setw(4) << val << setw(4) << mask << setw(4) << newval

<< setw(4) << (char) val << setw(4) << (char) newval;return(0);}

109 223 77 m M


Notes: 252


Bitwise OR Operation

00101011 4310101010 17010101011 171 Remember we’re adding, now

Why would we want to do this ?Encoding / Decoding AlgorithmsCommunications Error Checking (CRC)Manipulating TCP/IP packet addressesSub-net masks on Internet firewalls (198.200.78.41)Display Graphics ManipulationsMaster Bit NotationFile Allocation Tables on some machines

262,000 tracks, 1 bit for each track=32750 bytes7168 bytes/track uses 5 tracks for MBT


Bitwise OR Operation#include <iostream.h>#include <iomanip.h>

unsigned val=43;unsigned mask=170; // Bitwise OR Operationunsigned newval;

main(){

newval = val | mask;cout << setw(4) << val << setw(4) << mask << setw(4) << newval;return(0);}

Prints: 43 170 171


Notes: 253


Bitwise XOR Operation

Exclusive OR (one or the other but not both)

00101011 4310101010 17010000001 129 Remember we’re adding, Again


Bitwise XOR Operation#include <iostream.h>#include <iomanip.h>

unsigned val=43;unsigned mask=170; // Bitwise XOR Operationunsigned newval;

main(){newval = val ^ mask;cout << setw(4) << val << setw(4) << mask << setw(4) << newval;return(0);}

Prints: 43 170 129


Notes: 254


Complement Operation

Inverse function flips each bit (bitwise negation)

00101011 4311010100 212

11111111 25500000000 0

Why would we want to do this ?Encoding / Decoding AlgorithmsCommunications Error Checking (CRC)Manipulating TCP/IP packet addressesSub-net masks on Internet firewalls (198.200.78.41)Display Graphics Manipulations


Shifting Operations

Basics of the right shift

01011100 9200101110 4600010111 2300001011 1100000101 500000010 200000001 1

Notice it is a divide by two operation


Notes: 255


Shifting Operations

Basics of the left shift

01011100 9210111000 18401110000 11211100000 22411000000 19210000000 128

Notice it is a multiply by two operation


Shifting Example#include <iostream.h>#include <iomanip.h>unsigned val=92;int i;

main(){

for (i=0; i<9; i++){cout << setw(8) << val << endl;val = val << 1;}

return(0);}

Prints:92 184 368 736 46 23

Prints:92

1843687361472294458881177623552


Notes: 256


C++ Pointers


int x;

void main(void){

x=6000;cout << setw(8) << x << setw(18) << &x << endl;

}

Output:

6000 00477748 Verified 11/27/2003


C++ Pointers#include <iostream>using namespace std;

double d1;double d2;int x;int *iptr;double *dptr1;double *dptr2;

void main(void){

x = 100; iptr = &x; dptr1 = &d1;dptr2 = &d2;

cout << “ Address of x: " << &x << endl;cout << “ Address of iptr: " << &iptr << endl;cout << “ Contents of iptr: " << iptr << endl;cout << " Value of x: " << *iptr << endl;cout << "Contents of dptr1: " << dptr1 << endl;cout << "Contents of dptr2: " << dptr2 << endl;

}

Address of x: 00477738Address of iptr: 0047773CContents of iptr: 00477738

Value of x: 100Contents of dptr1: 00477750Contents of dptr2: 00477758

Verified 11/27/2003

Notice the length of the double is obviously 8 bytes based on the difference in the addresses


Notes: 257


Register class

#include <stdio.h> register x=0, var=0; // register classint y=0, count=0; // signed integers

int main(void){

for (x=0; x<10000; x++)count++;

for (y=0; y<10000; y++)count++;

.

.return(0);}

Notes: Uses very fast registers compared to memory

Register access 2 cycles

Memory access 12 cycles

Each cycle is one tick of the clock.


Register class

Register access 1 to 2 cyclesMemory access 12 to 20 cycles

10 to 12 times slower than register accessDisk access 5 milliseconds per I/O

2,000,000 times slower than register access

Each cycle is one tick of the clock..000000003 seconds per tick

1 / 400 MHz


Notes: 258


Generated Internal Code

Typical increment structure

loop: mov ax,count ; get initial valueinc ax ; increment registermov count,ax ; replace itmov dx,y ; load y into dxinc dx ; increment registermov y,dx ; store it backcmp dx,10000 ; test for exitjle loop ; play it again, Sam

Some machines have memory increment instructions, but, register operations are still faster than memory to memory instructions.


Generated Internal Code

Register class increment structure

clr ax ; clear ax registerclr dx ; clear dx register

loop: inc dx ; increment registerinc ax ; increment registercmp ax,10000 ; test for exitjle loop ; do it again

Six lines of code -- faster than the previous 8


Notes: 259


volatile Type Qualifier

Means a variable can be altered by some external process

volatile int counter = 0;volatile int memloc;

int main(void){.. Other C++ Code.}

Typically, a memory location. Also called a common area or common bank.


volatile Type Qualifier

Program A Program B Program C

volatile int counter

counter++ counter++ counter++


Notes: 260


Summary

Summary of Boolean Operations, Hex, Binary, Octal

Boolean ExpressionsEnumeration TypesBitwise OperatorsRegister ClassVolatile & Extern

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