1 Chapter 1 Introduction to Computer Programs 1.0 What is a Computer Program 1.0.1 Computer Is a machine that stores data (numbers, words, pictures), interacts with device (the monitor, printer) and executes program. Is a device capable of performing computations and making logical decisions at speed millions, and even billions, of times faster than human beings can. Example: personal computer, supercomputer. 1.0.2 Program Are sequences of instructions and decisions that the computer carries out to achieve a task. 1.0.3 Computer Programming A computer program tells a computer, in a minute detail, the sequence of steps that are needed to fulfill a task. The act of designing and implementing these programs is called computer programming. Computers process data under the control sets of instruction called computer programs. These computer programs guide the computer through orderly sets of action specified by people called computer programmers. The computer programmer does a great deal of programming. They must be expert in certain language. There are many programming languages such as Fortran, C, C++, Java, Cobol and many others. Every language has their own advantages and disadvantages. The choice of programming language is sometimes a complex decision. It depends on the needs of the program you are creating.
Transcript
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Chapter 1
Introduction to Computer Programs
1.0 What is a Computer Program
1.0.1 Computer
� Is a machine that stores data (numbers, words, pictures), interacts with
device (the monitor, printer) and executes program.
� Is a device capable of performing computations and making logical
decisions at speed millions, and even billions, of times faster than human
beings can. Example: personal computer, supercomputer.
1.0.2 Program
Are sequences of instructions and decisions that the computer carries out to
achieve a task.
1.0.3 Computer Programming
A computer program tells a computer, in a minute detail, the sequence of
steps that are needed to fulfill a task. The act of designing and implementing
these programs is called computer programming.
� Computers process data under the control sets of instruction called
computer programs.
� These computer programs guide the computer through orderly sets of
action specified by people called computer programmers.
� The computer programmer does a great deal of programming. They must
be expert in certain language.
� There are many programming languages such as Fortran, C, C++, Java,
Cobol and many others. Every language has their own advantages and
disadvantages.
� The choice of programming language is sometimes a complex decision. It
depends on the needs of the program you are creating.
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Preprocessor directive
1.1 Elements of Computer Program
� The following example present a simple C++ program:
/*This is a program to calculate the sum of 2 integer numbers*/ #include <iostream.h> main() { int num1, num2, sum; cout<<”Enter first number:”; cin>>num1; cout<<”Enter second number:”; cin>>num2; sum = num1 + num2; cout<<”Sum = “<<sum; return 0; }
1.1.1 Comments
� Programmers always placed comments, explanations or messages in their
program to help them and others to read and understand the programs.
� Comments in C++ are not executable.
1.1.2 The include Directive and Header Files
� #include <iostream.h> is called an include preprocessor directive.
This directive enables the program to use certain functions contained in
the external file. Example: iostream.h.
� As the file is placed before the program proper, it is called a header file
(with the extension .h).
� C++ provides many predefined functions or routines that are stored in
header files.
� Programmers will use one or more header files to simplify programming
and to reduce programming time.
� Each header file stores functions that are related to a particular
application. Example file iostream.h are cin and cout.
� There are other preprocessor directives. Example: define
Function Body
Comment
Function Name
Begin Block
End Block
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1.1.3 Functions
� All C++ programs are written in terms of functions.
� Functions are in fact the basic building blocks in C++.
� In C++, the program must have at least the function main().
� Every function must have a body enclosed in braces { }.
� The function body (also called block) can be of any size.
1.1.4 Declaration
� All variables in C++ must be declared prior to their use.
� Variables are simply references to memory locations.
� In addition to declaring variables we must also specify their types.
1.1.5 Reserve Words
� Reserve words are special words that have special meaning and they
cannot be used for any other purpose.
1.1.6 Console Input/Output
� We enter data into computer via the system console (the keyboard) by
using the function cin (console input) and the redirection operator >>.
� The function cout (console output) and the redirection operator <<
sends the output from a variable (some memory location) to the system
console (the monitor).
1.1.7 C++ Statements
� An executable statement in C++ must be followed by a semicolon (;).
1.2 The Importance of Programming
� Programming will help users to understand the computer.
� Programming will help users to increase the level of confident.
� It will help users to appreciate with what computer and programming can
be done to solve any problems.
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1.3 Good Programming Styles
� Good programming style is very important in order to make the program
easier to read and for maintenance process, especially when other
persons try to understand the program.
� The following guidelines are some tips that you can follow when you write
the program:
� Tabs are set every three spaces.
� Variable and method names are lowercase, with occasional
uppercase characters in the middle.
� Class names start with an Uppercase letter.
� Constant names are UPPERCASE, with an occasional
UNDER_SCORE.
� There are spaces after keywords and surrounding binary operators.
� Braces must line up horizontally or vertically.
� No magic numbers may be used.
� Every method, except for main and overridden library methods,
must have a comment.
� At most 30 lines of code may be used per method.
� No continue or break is allowed.
1.3.1 Naming Convention
� The following rules specify when to use uppercase and lowercase letters
in identifier or variable names:
� All variables and method names and all data fields of classes are in
lowercase. (Maybe with an occasional uppercase in the middle); for
example, firstPlayer.
� All constants are in uppercase (maybe with an occasional
UNDER_SCORE); for example, CLOCK_RADIUS.
� All classes and interface names start with uppercase and are
followed by lowercase letters (maybe with an occasional
UpperCase letter); for example BankTeller.
� Names must be reasonably long and descriptive.
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1.3.2 Indentation and White Space
� Use tab stops every three columns.
� Use blank lines freely to separate parts of a method that are logically
distinct.
� Use a blank space around every binary operator
� Example:
//Good
x1 = (-b – sqrt(b * b – 4 * c)) / (2 * a);
//Bad
x1=(-b-sqrt(b*b-4*c))/(2*a);
� Leave a blank space after (and not before) each comma or semicolon. Do
not leave space after a parenthesis or bracket in an expression.
� Leave spaces around the (. . .) part of an if, while, for or catch
statement.
� Example:
if (x == 0) y = 0;
f(a, b[i]);
� Every line must fit on 80 columns. If you must break a statement, add an
indentation level for the continuation. Start the indented line with an
operator (if possible).
� Example:
a[n] = …………………………………………………………………………… + ………………………………………; � If the condition in an if or while statement must be broken, be sure to
brace body, even if it consists of only one statement:
� Opening and closing braces must line up, either horizontally or vertically:
� Example:
while ( i < n ){ ………. }
OR while ( i < n ) { : : }
1.3.4 Unstable Layout
� Do not use // comments that extend for more than two lines.
� Example:
// comment – don’t do this // more comment // more comment
� Use /* …… */ comment.
� Example:
/* comment more comment more comment */ OR /* comment more comment more comment */
1.4 Relationship Between Compilers, Interpreter and Programs
� Programmers writing in a high-level language enter the program’s
instructions into a text editor.
� Text editor is similar to a word processor, except the files are saved in a
basic text format without the font and formatting codes word processor
use.
� The files saved by text editors are called text files.
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� A program in the form of a high-level language is called source code.
� Programmers must have their high-level programs translated into the
machine language that microprocessor understands.
� The translation may be done by interpreter or compilers.
� The resulting machine language code is known as object code.
1.4.1 Interpreters
� Is a program that translates the source code of a high-level language into
machine language.
1.4.2 Compilers
� Is another program that translates a high-level language into machine
language.
� A compiler, however, makes the translation once, then save the machine
language so that the instructions do not have to be translated each time
the program is run.
� To run a C++ program, we must first create it, then compile it, then link it
with other modules (or other compiled programs), and finally run it.
� The figure bellow shows the steps involve in using compiler:
Tool Step Product
Editor Edit
Source Code
Compiler Compile
Object file
Linker Link Library
Executable file
Run
Result/Output
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Explanation:
After you have created the source code, you compile it using the C++
compiler. The compiler translates your C++ instructions into a machine
readable form. The compiled program is called the object file.
Besides compiling the source code into an object file, the compiler also
generates information necessary for the linker. The linker links the object file
generated by the compiler and any other object file your program may request
into a final executable file that can be run as many times as desired without
having to be translated again.
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Chapter 2
Problem Solving Phase
2.0 Introduction
� Many programmers develop programs by using the following steps
� Analysis
� Design
� Implementation
� Testing or Debugging
� Maintenance
� Problems can be defined as unsolved problems that required the problem
solving or getting results and normally we need to think and skills to get
the correct solutions.
� Solving process will involve the sequence of acting defined clearly. When
we implement the process, we will get the result.
� Problem Solving can be defined as a process to convert the problem to
be solved into a solution by using any strategies, techniques and tools that
can be used to solve the problem, and finally that will give the good
defined clearly solutions.
� Any problems can be solved by using computer. The following criteria can
be used in order to make choices:
� The problems have varieties of input.
� The problems have varieties of output.
� The complexities of the problems.
� The times consuming based on the problem given.
� When we using the same technique repeatedly for the same
problem but with different input.
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2.1 Analysis
� Is a process to convert the problem statements into the solution for the
problem given.
� It can be done by using the knowledge and realize our abilities to choose
and use any strategies, solutions, techniques and tools to define the main
problem.
� The result from the action taken are:
� The clearly defined problem statements and understood.
� Unclearly statements or assuming will be clearly defined.
� Constrains can be defined.
� In this phase you have to understand and identify the following matters:
i. Input for the problem: it is several pieces of data that needed to
solve the problem.
ii. Expected output or result from the problem solving.
iii. Identify constrains and occurrences that may be exist.
iv. Identify the formula needed.
2.2 Design
� An algorithm is a set of sequential instructions that are followed to solve a
problem.
• An algorithm must fulfill the following requirements:
i. Has an input.
ii. Produce at least one output.
iii. Must be clear.
iv. Must be correct and can solve the problems.
v. Infinite.
vi. Efficient
vii. Common
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• Two types of algorithm:
(i) Pseudocode
� Is an artificial and informal language that helps programmers
develop algorithms.
� It is use such as English language or Malay language.
� The purpose of pseudocode is to make humans who do not
understand computer programming can easily understand the flow
of the problem solving.
� Pseudocode are using for:
� Design an algorithm
� To communicate with human.
� To use algorithm as a program code.
� To correct logic error in program code.
� Program documentation for maintenance purposes and future
reference
� An example for pseudocode:
//To calculates income tax payment. Begin Input salary Calculate incomeTax Print incomeTax End
(ii) Flow Chart
� It is represents by using geometry shapes with connected line.
� Example of flow chart:
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2.3 Implementation
� An algorithm’s is next translated into program code.
� A top-down approach to coding the program is followed.
� We begin by writing the main function, and then write the functions on
which the main function depends.
� Errors can be made during coding that can prevent the program from
successfully compiling and linking.
� A common error is called a syntax error.
2.4 Testing or Debugging
� Testing and debugging is an important step that is to often ignore.
� Programs typically fail to operate 100% correctly the first time they are
compiled or interpreted.
� Logics errors and other hidden problems called bugs must be located
� Software must be tested and “debugged” to make sure the output is
correct and reliable.
� One way to test a program is to provide input for which the results are
known.
Begin
Input salary
Calculate incomeTax
Print incomeTax
End
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� A type of error that can cause your program to stop running (or crash) is
called a run-time error.
2.5 Maintaining and Documenting
� Programmers must document their work so that that they and other
programmers can makes changes or updates later.
� Documentation may also have to be written for the program’s users.
� Maintenance is an important part of the programming process.
� Most programs are written to help with a task.
� As a task changes, the program must also change.
� Users are likely to request that addition and changes be made to the
program.
� Maintaining a program is an important part of the process because it
keeps the programmer’s work up to date and in use.
� Bugs may be found that were not uncovered during the testing and
debugging phase.
� It also possible that better ways to accomplish a task in the program may
be discovered.
� The steps of the programming process may be repeated in order to refine
or repair an existing program.
2.6 Introduction to Algorithm Design.
� Algorithm design is a most important in a program development. Its can
help to represent the flow of the program clearly.
� An algorithm is a set of sequential instructions that are followed to solve a
problem. It must have input and output.
� Two types of algorithm that are normally use:
i) Flow Chart
ii) Pseudocode
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2.6.1 Flow Chart
� It is represents by using geometry shapes with connected line.
� The following geometry shapes are using to represent flow chart.
Shapes Function
Begin/End
Process
Input/Output
Control Structure
Continue to the next page
Continue to the same page
Flow control
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Example: To calculate the sum of two numbers and to update the counter.
� The following algorithm represent for all cases:
(i) Sequential
(ii) Selection
a) if
Example: If student’s mark is greater than or equal 50 print “PASS”.
Statement_1
Statement_2
Statement_n
sum <- A + B
counter <- counter + 1
Process_1 Selection
statement
False
True mark >=60
Print “PASS”
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b) if – else_if
Example: If student’s mark is greater than or equal 50 print “PASS”, otherwise “FAIL”
False True mark >= 50
Print “FAIL” Print “PASS”
False True
Process_1
Selection
Statement
Process_2
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c) Nested if-else_if
Example: Print the grade based on the following table: Marks Grade 80 – 100 A 70 – 79 B 60 – 69 C 50 – 59 D 0 – 49 F
False
False
mark>=
80
True Print
“Grade A”
mark>=
70
True Print
“Grade B”
False
mark>=
60
True Print
“Grade C”
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d) switch
(iii) Looping
a) for
False
False
False
True
True
True case_1
Process_1
case_2
case_n
defaut
break
Process_2 break
Process_n break
False
True Loop
continuation
condition
Process Increment
Initial value
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(iv) do-while
Example: Calculate the sum of integer numbers (0-10)
False
True counter
<=10
sum = sum +
counter
counter =
counter + 1
sum <- 0
counter <-0
False
True Expression
Statement
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(v) while
False
True
Example: Calculate the sum of 10 numbers (0 – 9).
Expression Statement
False
True i !=
counter
sum <- sum + i
i<- i + 1
sum <- 0
i<-0
counter<-10
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2.6.2 Pseudocode
� The following algorithm represent for all cases:
i) Sequence
Begin Statement_1 Statement_2 Statement_3 . . . Statement_n End
Example: Calculate income tax.
Begin Input annualIncome Input status Calculate incomeTax Print incomeTax End
Example: Print the positive number based on the input given.
False
True number>0 Print
“number”
number <- number-
5
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ii) Selection
a) if
if expression
Statement
Example: Print the status of student if the passing marks is 50
Begin Input marks
if marks >= 50 Print “PASS” End
b) if-else
if (expression)
Statement_1
else
Statement_2
Example: Determine the status (PASS or FAIL) of student if the
passing marks is 50.
Begin Input marks if marks >= 50
Print “PASS” else Print “FAIL” End
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c) Nested if - else_if
Begin Input marks
if marks > 80 Print “A” else_if marks > 70 Print “B” else_If marks > 60 Print “C” else_if marks >50 Print “D” else Print “F” End
d) switch
Example: to print the number based on the input given
Begin Input number switch number case 1 Print “ONE” break case 2 Print “TWO” break case 3 Print “THREE” break default “INVALID NUMBER” End
Example: Print the grade based on the following table: Marks Grade 80 – 100 A 70 – 79 B 60 – 69 C 50 – 59 D 0 – 49 F
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iii) Looping
a) while statement_1
while expression while expression statement begin_while
looping body statement_1 end_while
Example: To calculate the average marks for five students.
Begin Set counter=1 and total=0 while counter<=5 begin_while Input marks total <- total + marks counter <- counter + 1 end_while average <- total / counter Print total, average End
b) do…while
Example: To calculate the total of numbers from 0 until the input
given.
Begin Input number counter = 0; do total = total + counter counter = counter + 1 while counter <= number Print “total” End
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End
False
True
Begin
Input num1
Input num2
If num1 >
num2 max=num1
max=num2
Print max
2.7 Example of Solutions by Using Algorithm
• The following examples are the solution that involves the using of
algorithm.
Example 1:
Determine the maximum value between two numbers.
Solution:
i) Pseudocode
Begin Input num1 Input num2 if num1>num2 max<-num1 else max<-num2
End
ii) Flow Chart
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Example 2: Calculate the total and average of two numbers.
i) Flow Chart ii) Pseudocode Begin Input num1, num2 total <- num1 + num2 average <- total/2 Print total, average End
2.8 Example of Problem Solving
Example 1:
“Write a program that reads in the name and hourly wage of an employee.
Then ask how many hours the employee worked in the past week. Compute
the pay. Any overtime work (over 40 hours per week) is paid at 150 percent of
the regular.”
Solution:
Analysis
� To calculate the payment of salary for the employee based on the
hours of working.
� Input and output specification requirements:
� Name, hourly wage and working hours as an input entered by
user.
Begin
Input num1
Input num2
End
total -< num1+num2
average = total / 2
Print total
Print average
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� Calculate payment of salary for the employee
� Solving techniques:
� Get the formula to calculate the payment of salary for the
� The output of division by using operator ‘/’ is depend on the type of its
operand.
� Integer Division
� It happens when both operand are integer values. The value can be
constant or identifier.
� If the value for the output of division is floating point number, its will
discard the remainder. The output is integer value.
� Example:
Expression Output
25 / 5 5
13 / 2 6
25 / 3 8
� Non Integer Division
� It happens when at least one of the operand is a real number.
� The output is a real number value.
� Example:
3.6.2 Modulo Operator
� The value of output for modulo ‘%’ operator is its remainder from the
process of division to integer value.
� Both of operands must be integer value.
� Example:
Expression Output
5 % 2 1
8 % 4 0
Expression Output
5 / 2.5 2.0
5.0 / 10 0.5
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3.6.3 Hierarchy of Operators
� The hierarchy operator precedence from highest to lowest is summarized
in the following table:
Operator Category Operator
Unary -, --, ++
Arithmetic multiply, divide, remainder *, /, %
Arithmetic add and subtract +, -
Relational operators <, <=, > >=
Equality operators ==, !=
Logical AND &&
Logical OR ||
� The arithmetic expression will be evaluated based on the operator
precedence. The highest operator precedence will be evaluated first.
� Example:
2 + 7 * 5
= 2 + 35
= 37
� If the level of operator precedence at the same level, the expression will
be evaluated from left to right.
� Example:
2 * 3 / 2
= 6 / 2
= 3
� As in algebra, C++ expression can be complex. Parentheses can be used
to force the order of evaluation. So, the evaluation is not based on the
operator precedence.
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� Example:
(9 – (3 + 2)) * 3
= (9 – 5) * 3
= 4 * 3
= 12
� In C++, we have to be careful when we try to represent arithmetic
expression. We also must be careful to the hierarchy level of operator
precedence. If we careless about it, the evaluation result may be incorrect.
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Chapter 4
Sequential Control Structure
4.0 Assignment Statement
� In C++, we can represent the expression by using the following
assignment statement:
i. Simple Assignment Statement.
ii. Doubly Assignment Statement.
iii. Compound Assignment Statement.
4.0.1 Simple Assignment Statement
� Arithmetic expression is an example of simple assignment statement.
� The computer will evaluate the right expression and will assign the value
of output to the left variable.
� Example:
i. average = (5 + 5 + 5) / 3;
ii. salary = 16.5 * 30;
� The expression can be constant or variable values and also can be
evaluated, so that the variable must be assigned with any values.
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� Example:
void main()
{
//Calculate the price of product after discount
float price, discount, payment;
price = 12.60
discount = 0.05;
payment = price * discount;
cout<< “Amount of payment: RM ” <<payment;
}
4.0.2 Doubly Assignment Statement
� In C++, beside constant and variable, one expression can be from another
expression, which means we can do several processes in one expression.
� Example:
A = B = C = 40;
4.0.3 Compound Assignment Statement
� When we write the program, sometimes we need to modify certain value
for any variable, which is the origin value is added or multiply and then the
result will be assigned into the origin variable. We always write the code as
follows:
� Example:
count = count + 5;
� if the origin count is 20, the right expression (count + 5) will
produce the result of 25. This value will be assigned into count
variable. That means the origin value (20) will lose and its replace
with 25.
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� In C++, this statement can be represented by using compound operator.
Refer to the following table:
Operator Example Meaning
+= count += 5 count = count + 5
-+ count -= 5 count = count – 5
*= count *= 5 count = count * 5
/= count /= 5 count = count / 5
%= count %= 5 count = count % 5
� The hierarchy of precedence for compound operator is the lowest which
means this expression will be evaluated at last.
4.1 Input/Output Statement
� We enter data into the computer via the system console (the keyboard) by
using the function cin (console input) along with the redirection operator
>> while the function cout (console output) along with the redirection
operator << is used for sending output to the monitor.
4.1.1 cin Statement
� This statement is used to read input from keyboard.
� Syntax:
cin >> variable;
� variable – refer to any valid identifier only
� Example:
VALID
cin >> height;
INVALID
cin >> 15
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� When entering data from the console, it is always good to include suitable
prompts (message) so that we know what we are doing at the console.
� Example:
cout << ”Enter height: “;
cin >> height;
4.1.2 cout Statement
� This statement will send the data into output device such as monitor based
on the format given.
� Syntax:
cout << ”The list of output”;
� The list of output can be identifier, constant,
expression or combination of all.
� Example:
cout << “Enter your age:”;
� When sending output from the variable to the monitor or to the printer, it is
often desirable to send message such as titles or labels along with the
output.
� Example:
cout << “\nYear of birth:”<<year_birth;
� Notice that the format string has two additional characters: \n. It is called
a newline escape sequence.
� An escape sequence, if used, must appear within the format string
enclosed by “ “.
� It is used for controlling or formatting the output.
� Escape sequence begin with the backslash \.
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� The following table shows some escape sequence.
Code Meaning
\a Audible bell
\b Backspace
\f Formfeed
\n Newline
\r Carriage return
\t Horizontal tab
\\ Backslash character
\’ Single quote character
\” Double quote character
\0 NULL ASCII 0
4.1.3 Example of program:
#include<iostream.h>
void main()
{
float value;
float result;
cout<<”\n Enter a number: ”;
cin>>value;
cout<<”\n The value was entered: ”<<value;
result = value * value;
cout<<”\n The result for power of two is: ”<<result;
}
Example of input and output:
Enter a number: 4 //4 is the value from user input
The value was entered: 4
The result for power of two is: 16
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4.2 Arithmetic Expression
� Arithmetic expression contain one or more arithmetic operator:
� Example:
i. 2 + 2
ii. 14 * 2 * 5
iii. 12 – 6 + 13 * 4/3
� In C++, we have to represent the algebra expression by using the valid
syntax. The following table shows the valid expression.
Algebra Expression Valid expression in C++
14 – 5 + 6 14 – 5 + 6
16 – 8
2
16 – 8 / 2
15 + 5 + 7
2
(15 + 5 + 7) / 2
42 pow ( 4 , 2 )
√ ( x – y ) sqrt (x – y )
x – y abs ( x – y )
4.2.1 Increment And Decrement Operator
� C++ provides the ++ unary increment operator and the -- unary
decrement operator.
� The table summarized the above operators :
Operator Called Sample expression
Explanation
++ Preincrement ++a Increment a by 1, then use
the new value of a in the expression in which a
resides.
++ Postincrement a++ Use the current value of a
in the expression in which a resides, then increment a
by 1.
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-- Predecrement --b Decrement b by 1, then use
the new value of b in the
expression in which b
resides. -- Postdecrement b-- Use the current value of b
in the expression in which b resides, then decrement b
by 1
� If an increment or decrement operator is placed before a variable, it is
referred to as the preincrement or predecrement operator, respectively.
� If an increment or decrement operator is placed after a variable, it is
referred to as the postincrement or postdecrement operator, respectively.
� Preincrementing (predecrementing) a variable causes the variable to be
incremented (decremented) by 1, then the new value of the variable is
used in the expression in which it appears.
� Postincrement (postdecrementing) a variable caused the current value of
the variable to be used in the expression in which it appears, then the
variable value is incremented (decremented) by 1.
� Example:
#include<iostream.h> void main() { int c; c = 5; cout<< c << endl; //print 5 cout<< c++ << endl; //print 5 then postincrement cout<< c << endl << endl; //print 6 c = 5; cout<< c << endl; //print 5 cout<< ++c << endl; //preincrement then print 6 cout<< c << endl; //print 6 }
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4.2.2 Types of Arithmetic Expression
� In C++, there are many different types of data. When assigning the type
into arithmetic expression, the compiler will follow the rules bellows:
i. If there are more than one operand in arithmetic expression are
double, so the type of output is double.
ii. If there are all operands in arithmetic expression are int, so the
type of output is int.
iii. In arithmetic expression assignment, the type for statements and
values stored inside variable on the left assignment operator will
refer to the same type of its variable.
Example:
int three; double one, two; one = 3.4; three = 12;
if we have the following expression statement: two = one + three; The value for output is 15.4 which is type of double. It
happens because one is a variable type of double, so the variable three type of int will be changed into real number and the output will be real number.
4.2.3 The cast function
� The function cast may be used to force an expression to be of a specific
data type.
� Syntax:
(type) expression;
type (expression);
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� Example:
int b; double a; a = 3.4; b = 12;
Expression Output a = (int)(a + b) 15 a = a + (double)b 15.4 a = (int) a % b 3 a = b % (int)a 0 a = (int)a + b 15
� Example of program:
Example 1:
To calculate the circumference and the area of a circle
#include<iostream.h> #include<conio.h> #define PI 3.14159 #define TWO 2.0 void main() { float area, circum, radius; cout<< "Enter radius: "; cin>> radius; area = PI * radius * radius; circum = TWO * PI * radius; cout<< "\nCircumference : "<<circum; cout<< "\nArea : "<< area; getch(); }
51
Example 2 :
A person invests RM1000.00 in a saving account yielding 5% interest.
Assuming all interest is left on deposit in the account, calculate and print
the amount of money in the account at the end of each year for 10 years.
Use the following formula for determining these amounts:
a = p(1 + r)n
where
p is the original amount invested (i.e, the principal)
r is the annual interest rate
n is the number of years
a is the amount on deposit at the end of the nth year.
Solution:
#include <iostream.h> #include <conio.h> #include <iomanip.h> #include <math.h> void main() { double amount; //amount of deposit double principal = 1000.0;//starting principal double rate = 0.05; //interest rate cout<< "Year" << setw(21) << "amount on deposit" <<endl; for(int year = 1; year <= 10; year++) { amount = principal * pow( 1.0 + rate, year); cout<< setw( 4 ) << year << setiosflags(ios::fixed |ios::showpoint) << setw ( 21 ) << setprecision( 2 ) << amount << endl; } getch(); }
52
Exercise
1. Write a program that asks the user to input the hours, minutes, and second, then
convert it into minutes and seconds only.
2. Write a program to read the weight in pound and convert it into kilogram and
gram (hint: 1 pound = 0.453592 kg and 1 pound = 453.59237 gm)
3. Write a program to calculate the area which is labeled (black):
4. The area of triangle can be calculated by knowing the border of a, b and c.
Given the following formula:
area = s (s – a) (s – b) (s – c)
Where is;
s = (a + b + c) / 2
Calculate the area of triangle by using the above formula.
5. Write a program that prompts the user for two numbers, then prints
� The sum.
� The difference.
� The average.
� The distance (absolute value of the difference).
� The maximum.
� The minimum.
d
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6. Write a program that asks the user for the length of the sides of a square. Then
print
� The area and perimeter of the square
� The length of the diagonal (use the Pythagorean theorem)
7. Write a program that reads two times in military format (0900, 1730)and prints the
number of hours and minutes between the two times. Here is a sample run.
Please enter the first time: 0900
Please enter the second time: 1730
8 hours 30 minutes
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Chapter 5
Selection Control Structure
5.0 Introduction
� The selection structure allows instruction to be executed non-sequentially.
� It allows the comparison of two expressions, and based on the
comparison, to select a certain course of action.
� C++ provides two selection structures: if-else and switch.
5.1 Relational and Logical Operators
� Relational operation is used to compare the value of two variables, which
are equal, less than, greater then and so on.
� This operation contains two operands, which is can be value of identifier,
constant or both combinations.
� The six relational operators in C++ are shown below:
Operator Meaning
< Less than
<= Less than or equal
> Greater than
>= Greater than or equal
== Equal
!= Not equal
� The result of evaluation of a relational operation is either true (represented
by 1) or false (represented by 0).
55
� Example:
Relational Expression Value
5 < 9 1
7 == 8 0
6 ! = 7 1
� To evaluate the combination of relational operation on different set of
identifiers, we can perform logical operation by using the logical operators.
� The tree logical operators in C++ are shown bellow:
Operator Meaning
&& AND
|| OR
! NOT
� The following table represents the function for each logical operator. This
table known as True Table. 0 values represent false and 1 represent
true.
� Truth table for AND operator:
State 1 State 2 Value
1 0 0
0 1 0
0 0 0
1 1 1
� Truth table for OR operator:
State 1 State 2 Value
1 0 1
0 1 1
0 0 0
1 1 1
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� Truth table for NOT operator:
State 1 Value
1 0
0 1
0 1
1 0
5.2 If Statement
� If statement construct enable your program to choose from several
alternatives and executes only one statement.
� In C++, we will use relational and logical operator to represent if
statement.
� Syntax:
if (expression)
statement;
� Execution:
The statement will be executed if the expression value is true or 1
� Normally, the expression is a relational expression that contain of true or
false values.
� Example:
if (age < 3)
cout<< “Baby”;
***Note: After if statement no comma (;)
� If statement can have many statements known as compound statement.
Compound statement must have open bracket “{“ and close bracket “}”.
57
� Example:
if (a<b) {
min = a;
cout << “a is smaller than b”;
}
5.1.1 if-else statement
� Syntax:
if expression
statement_1 else statement_2
� Execution:
statement_1 will be executed if the expression value is 1
statement_2 will be executed if the expression value is 0
� Example:
a) if (cgpa < 2.0 ) status = ‘F’;
else status = ‘P’;
b) if ( choice == 1) gender = ‘M’;
else gender = ‘F’;
c) if ( a < b ) { min = a; // compound statement max = b; // executed if a<b
} else{
min = b; // compound statement max = a; // executed if a>=b }
if (expression_1) if (expression_2) if (expression_3) statement_1; else statement_2; else statement_3; else statement_4; � In this nested form, expression_1 is evaluated. If it is zero,
statement_4 is executed and the entire nested if statement is
terminated; if not, control goes to the second if (within the first if) and
expression_2 is evaluated. If it is zero, statement_3 is executed; if
not, control goes to the third if (within the second if) and
expression_3 is evaluated. If it is zero, statement_2 is executed; if
not, statement_1 is executed.
� Only ONE of the statements is executed.
� When using the above form care must be taken to properly match the ifs
within the correct elses.
� One simple rule to follow is: always match an else with the nearest if
before the else.
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5.5 Minimum and Maximum
� Example:
//Finding the maximum and minimum of three integers
#include <iostream.h> #include <conio.h> int maximum (int, int, int); int minimum (int, int, int); int main() { int a, b, c; cout << "Enter three integers: "; cin >> a >> b >> c; cout << "Maximum is: " << maximum( a, b, c)<< endl; cout << "Minimum is: " << minimum( a, b, c)<< endl; getch(); return 0; } int maximum (int x, int y, int z) { int max = x; if (y > max) max = y; if (z > max) max = z; return max; } int minimum ( int x, int y, int z ) { int min = x; if ( y < min ) min = y; if ( z < min ) min = z; return min; }
67
Exercise
1. The cost of an international call from New Zealand to New Delhi is calculated as
follow: connection fee, $1.99; $2.00 for the first three minutes; and $0.45 for each
additional minute. Write a program that prompts the user to enter the number of
minutes the call lasted and outputs the amount due.
2. Write a program that calculates and prints the bill for a cellular telephone
company. The company offers two types of service: regular and premium. Its
rates vary depending on the type of service. The rates are computed as follows:
Regular service : $10.00 plus first 50 minutes are free. Charges for over 50
minutes are $0.20 per minute.
Premium service: $25.00 pus:
a) For calls made from 6.00 a.m to6.00 p.m, the first 75 minutes are free;
charges for over 75 minutes are $0.10 per minute.
b) For calls made from 6.00 p.m to 6.00 a.m, the first 100 minutes are free;
charges for over 100 minutes are $0.05 pr minute.
Your program should prompt the user to enter an account number, a service
code (type char), and the number of minutes the service was used. A service
code of r or R means regular service; a service code of p or P means premium
service. Treat any other character as error. Your program should output account
number, type of service, number of minutes the telephone service was used, and
amount due from the user.
For the premium service, the customer may be using the service during the day
and at night. Therefore, to calculate the bill, you must ask the user to input the
number of minutes the service was used during the day and the number of
minutes the service was used at night.
68
Chapter 6
Repetition/Iteration Control Structure
6.0 Introduction
� The repetition or iteration structure permits a sequence of instructions to
be executes repeatedly until a certain condition is reached.
� In C++, there are three forms, while, do-while and for.
6.1 while statement
� The general form of while statement:
� Syntax:
while (expression)
statement;
� The statement can be either a simple or compound statement.
� The expression, called a loop condition, acts as a decision-maker
and is a logical expression.
� The expression provides an entry condition. If it initially evaluates to
true, the statement executes.
� The loop condition-the expression- is then reevaluated. If it again
evaluates to true, the statement executes again.
� The statement (body of loop) continues to execute until the expression
is no longer true.
� A loop that continues to execute endlessly is called an infinite loop.
� To avoid an infinite loop, make sure that the loop’s body contains one or
more statements that ensure that the loop condition-the expression in
the while statement – will eventually be false.
69
� Example 1:
i = 0;
while (i <= 9){
cout<< i ;
i++;
}
� Example 2:
cin>> n;
while ( n > 0 ){
cout << n;
n -= 5;
}
//if the input value is negative or zero, so the
//while compound statement will not be executed.
6.1.1 Counter-Controlled while Loops
� When we know exactly how many pieces of data (data entries) need to be
read, the while loop assumes the form of a counter-controlled while
loop.
� In this case, the while loop might look like the following:
counter = 0;
while ( counter < N)
{ .
.
counter++;
.
.
}
� Suppose the program has N data items. You can set up a counter
(initialize to 0 before the while statement) to track how many items have
been read.
70
� Before executing the body of the while statement, the counter is
compared with N. The value of N can be determined in many ways such
as input by user. If the counter < N, the body while statement
executes.
� The body of loop continues to be execute until the value of counter >=
N. Thus, inside the body of the while statement, the value of the
counter increments after it reads a new item.
� Example:
#include <iostream.h>
void main()
{
int limit, number;
int counter = 0;
int sum = 0;
cout << "Enter data for processing: ";
cin >> limit;
while (counter < limit)
{
cout << "\nEnter data " << counter << ": ";
cin >> number;
sum = sum + number;
counter++;
}
cout << "\nThe sum of " << limit << " number = "
<< sum <<endl;
if ( counter != 0)
cout << "\nThe average = " << sum/counter; else
cout << "\nNo input";
}
71
6.1.2 Sentinel-Controlled while Loops
� You might not know how many pieces of data (or entries) need to be read,
but you do know that the last entry is a special value, called a sentinel
and this type is called a sentinel-controlled while loop.
� A while loop might look like the following:
Input the first data item into variable
while (variable != sentinel)
{
.
.
input a data item into variable
}
� In this case, you have to read the first item before entering the while
statement.
� If this items does not equal the sentinel, the body of the while
statement executes.
� The while loop continues to execute as long as the program has not read
the sentinel.
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� Example:
#include <iostream.h>
#include <conio.h>
void main()
{
int number;
int sum = 0;
int count = 0;
int SENTINEL = -999;
cout << " Enter numbers ending with " <<SENTINEL;
cout << "\n Enter number: ";
cin >> number;
while (number != SENTINEL)
{
sum = sum + number;
count++;
cout << "\n Enter number: ";
cin >> number;
}
cout << "\n The sum of " << count << " numbers ="
<< sum;
if ( count != 0)
cout << "\n The average = " << (sum / count);
else
cout << "\nNo input";
}
73
6.1.3 Flag-Controlled while Loops
� A flag-controlled while loop uses a boolean variable to control the loop.
� The flag-controlled while loop takes the following form:
bool found = false;
while (!found)
{
.
.
if (expression)
found = true;
.
.
}
� The variable found, which is used to control the execution of the while
loop, is called flag variable.
6.2 for Statement
� The for loop is typically called a counted or indexed for loop.
� The for loop has the general form:
for (initialization; expression; incrementation)
statement;
� The initialization part typically refers to the initial value (if
any) given to a loop variable or counter. But it can also include the
initialization of any other variable. This initialization
part is carried out just once at the beginning of the loop.
74
� The expression part determines whether the loop execution
should be continued. If the expression is zero (false), the for loop
is terminated; if it is not zero (true), the for statement (which can
take the form of a block) is executed.
� The incrementation part typically increments (or decrements)
the loop counter variable. This is done after the for statement is
executed. This part, like the initialization part, can also include the
incrementation of other variables.
� Example:
int sum = 0;
for (int i = 0; i < 20; i++)
sum = sum + i;
cout << “Sum of the first 20 numbers = “;
cout << sum;
� The for loop is executed as follows:
� After the one-time initialization, the expression is first
evaluated.
� If it is zero (false), the for loop is terminated; if it is not zero (true), the
statement in the loop is executed, and then the incrementation is
performed.
� The condition expression in the for loop is again evaluated and the
process is continued until the expression become zero (false).
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6.3 do…while Statement
� The general form of a do…while statement is:
do{
statement;
}while (expression);
� The do-while statement can be either a simple statement or a
compound statement. If is a compound statement, enclose it between
curly braces.
� The expression is evaluated after the statement is executed. This
means the statement in the do-while will be executed at least once.
� In the while statement, the statement will not be executed if the
� In this example, the program displays the menu and the requests a
selection.
� If the selection is 1, 2, or 3, the menu is displayed again, otherwise, the
loop is terminated.
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6.4 Nested Loops
� All of the repetition loop discussed so far can also be nested ( a while
loop within another while loop, a do-while loop within another do-
while loop, and a for loop within anther for loop) to any degree.
� The nesting of loops provides power and versatility required in some
applications.
� Example:
#include <iostream.h> #include <conio.h> void main() { for (int i = 1; i < 5; i++) { cout << "\n" <<i; for (int j = i + 1; j < 5; j++) cout << j; } getch(); }
77
6.5 Algorithms: Minimum, Maximum, Counter, Total and Average
� Example of Pseudocode:
BEGIN
SENTINEL = 0
max = 0
min = 999
total = 0
count = 0
INPUT number
WHILE ( number != SENTINEL)
START_WHILE
total = total + number
count = count + 1
IF number > max
max = number
IF number < min
min = number
INPUT number
END_WHILE
IF count != 0
average = total / count
ELSE
PRINT “ No input”
PRINT count, total, min, max, average ;
END
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� Example of program:
#include <iostream.h> #include <conio.h> void main() { int number; int SENTINEL = 0; int max = 0; int min = 999; int total = 0; int count = 0; cout << " Enter numbers ending with " <<SENTINEL; cout << "\n Enter number: "; cin >> number; while ( number != SENTINEL ) { total = total + number; count++; if (number > max) max = number; if (number < min) min = number; cout << "\n Enter number: "; cin >> number; } cout << "\n The total of " << count << " numbers = " << total; cout << "\n Maximum number: " << max; cout << "\n Minimum number: " << min; if ( count != 0) cout << "\n The average = " << (double)total / count; else cout << "\nNo input"; getch(); }
79
Exercise
1. Generate the following “pyramid” of digit by using nested loops and develop a
formula to generate the appropriate output for each line.
1 232 34543
4567654 567898765
2. Write the programs to print the following patterns:
� When a function is called, the program temporarily leaves the current
function to execute the called function.
� When the called function terminates, program control reverts to the calling
function.
� A function call consists of the name of the function, followed by a list of
arguments whose values are to be passed to the corresponding
parameters in the called function.
� The number and type of the arguments must correspond to the number
and type of the parameters in the called function.
85
� Example :
#include<iostream.h>
int num1, num2, sum;
void setData();
void printSum();
void main()
{
setData(); // (1)
printSum(); // (5)
}
void setData()
{
cout<< “Enter two numbers:”; //(2)
cin>>num1; //(3)
cin>>num2; //(4)
}
void printTotal()
{ sum = num1 + num2; //(6)
cout<< “Sum of two numbers is:”<<total; //(7)
}
NOTE: (1 …..7) – Flow of program executions.
86
7.3 Function Prototypes
� A function prototype specifies the number of arguments and their types as
well as the return value type of the function.
� The prototype is used to check if the number of arguments and their types
in the calling function correspond to the number of parameters and their
types in the called function every time the function is called.
� The general form of a function prototype declaration:
function_type function_name(parameter-list)
� parameter-list – consist of value types for every parameter
that can be input to the function. Name of parameter can be
ignored.
� Example:
float calcArea (int radius, int width);
or
float calcArea (int, int);
� Example:
#include <iostream.h>
void main()
{
void printComment(); // function prototype
int calTotal (int , int );//function prototype
printComment();
cout<< calTotal(5,2);
}
void printComment()
{ cout<< “Sum of two numbers is: “;}
int calTotal(int a, int b)
{
int total;
total = a + b;
return total;
}
87
7.4 Function Parameters
� In C++, the code and data defined in one function cannot interact with the
code and data defined in another function because the two functions are
independent, and therefore, have different scopes.
� In order to interact with one another, the functions pass arguments.
� The calling or invoking function passes argument (such as constants,
pointer or values of variable) to the called function.
� The called function receives the values passed to it and stores them in its
parameters.
� Once the values are received into the parameters, the parameters are
defined and thenceforth they behave very much like the local variables
declared within the function.
� The number and type of arguments passed by the calling function must
agree with the number and type of the parameters in the called function.
� Example:
#include <iostream.h> void display(int); main() //The main() function definition { int x = 12; //defines an integer variable display(x); //call display() and passes it x return 0; //return 0 to environment } void display(int y) //function definition { cout << y; //dislay the value of y }
The value 12 is passed from main() to display()
� Two way to invoke functions in many programming languages are passing
by value (call-by-value) and passing by reference (call-by-reference)
88
7.4.1 Passing by Values
� When an argument is passed call-by-value, a copy of argument’s value is
made and passed to the called function.
� Changes to the copy do not affect the original variable’s value in the caller.
� This prevents the accidental side effects that so greatly hinder the
development of correct and reliable software systems.
� Example:
multiple_two (3,80);
� Example of program:
#include <iostream.h>
void main()
{
int multiple_two (float,float);
float a, a_2, value;
a = 3;
a_2 = 80;
value = multiple_two (a, a_2);
cout << “The value of a_2 is : “ << a_2;
cout << “multiple of two is: ” << value;
}
int multiple_two (float i, float i_2)
{
i_2 = i * i;
return i_2;
}
� Explanation:
� When multiple_two function is called, the value of a(3) is
copied to i, and the value of a_2(80) is copied to i_2
� The function multiple_two will perform the calculation and get
the new result of i_2 (9)
89
� When the flow of process return to the calling function, the value of
i_2 will be returned to the calling function.
7.4.2 Passing by Reference
� With passing by reference, the caller gives the called function the ability to
directly access the caller’s data, and to modify that data if the called
function so chooses.
� A reference parameter is an alias for its corresponding argument.
� To indicate that a function parameter is passed by reference, simply follow
the parameter’s type in the function prototype by ampersand (&)
� Example:
int &count;
� Example:
//Comparing call-by-value and call-by-reference //with reference #include <iostream.h> int squareByValue( int ); void squareByReference ( int & ); int main() { int x = 2, z = 4; cout << “ x = “ << x << “ before squareByValue\n” << “Value returned by squareByValue: “ << squareByValue( x ) << endl; << “x = “ << x << “ after squareByValue\n” << endl; cout << “z = “ << z << “before squareByReference” << endl; squareByReference( z ); cout << “z = “ << z << “after squareByReference” << endl; return 0; }
90
int squareByValue ( int a ) { return a *= a; // caller’s argument not modified } void squareByReference (int &cRef ) { cRef *= cRef; // caller’s argument modified } RESULT x = 2 before squareByValue Value returned by squareByValue: 4 x = 2 after squareByValue z = 4 before squareByValue z = 16 after squareByReference
7.5 Using Predefined functions
� C++ compilers include predefined function, ready-to-use function to make
programming easier.
� The functions that come with your compiler are called library function.
� Library functions are just like functions you create and may be used in the
same way. The difference is that the source code for library functions does
not appear in your program.
� The prototypes for library functions are provided to your program using the
#include compiler directive.
91
� Example:
#include <iostream.h> #include <math.h> int main() { double base;
double exponent; double answer;
cout << "Enter the base: "; cin >> base; cout << "Enter the exponent: "; cin >> exponent; answer = pow (base, exponent);//built-in function cout << "The answer is: " << answer << endl; return 0; }
� Many C++ compilers provide basic math function. The header file math.h
Function Prototype Description
Abs int abs (int x) Returns the absolute value
of an integer
Pow double pow (double
x, double y)
Calculate x to the power of
y
Sqrt double sqrt (double
x)
Calculate the positive
square root of x)
� C++ also includes many functions for analyzing and changing characters.
The header file ctype.h.
Function Prototype Description
isupper int isupper (int c) Determines if a character is
uppercase.
islower int islower (int c) Determines if a character is
lowercase
isalpha int isalpha (int c) Determines if a character is a
letter (a-z, A-Z)
92
Isdigit int isdigit (int c) Determines if a character is a
digit (0-9)
toupper int toupper (int c) Converts a character to
uppercase
tolower int tolower (int c) Converts a character to
lowercase.
� We can control the precision of floating-point numbers, i.e., the number of
digits to the right of the decimal point, by using setprecision stream
manipulator. The header file iomanip.h
� Example:
#include <iostream.h> #include <math.h> #include <iomanip.h> int main() { double root = sqrt (2.0); int places; cout.setf(ios::showpoint); cout.setf(ios::fixed); cout << "\nPrecision set by the set” << “precision manipulator:\n"; for(places=0; places <= 9; places++) cout << setprecision (places) << root << '\n'; return 0; }
� The use left and right flags enable fields to be left-justified with padding
characters to the right, or right-justified with padding characters to the left,
respectively.
� setw stream manipulator to specify internal spacing. The header file
#include <iostream.h> #include <string.h> #include <conio.h> int main(void) { char *buf1 = "aaa", *buf2 = "bbb", *buf3 = "ccc"; int ptr; ptr = strcmp(buf2, buf1); if (ptr > 0) cout << "buffer 2 is greater than buffer 1\n"; else cout << "buffer 2 is less than buffer 1\n"; ptr = strcmp(buf2, buf3); if (ptr > 0) cout << "buffer 2 is greater than buffer 3\n"; else cout << "buffer 2 is less than buffer 3\n"; getch(); return 0; }
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7.6 Creating User-Defined Functions
� Example of program :
#include <iostream.h> #include <math.h> #include <conio.h> //Function prototype int sum( int , int ); int multiply (int , int ); int power ( int , int ); void maximum ( int , int ); void minimum ( int , int ); int main() { int num1, num2; cout << "Enter two numbers: "; cin >> num1 >> num2; //calling function int valueSum = sum( num1 , num2 ); cout << " \nThe value of sum : " << valueSum; cout << "\nThe value of multiply : " << multiply (num1 , num2 ); int valuePower = power( num1 , num2 ); cout << "\nThe value of power : " << valuePower; maximum ( num1 , num2 ); minimum ( num1 , num2 ); getch(); return 0; } //Function definition int sum ( int x , int y ) { return x + y ; }
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int multiply ( int x , int y ) { int value = x * y; return value; } int power ( int x, int y ) { return pow( x , y ); } void maximum ( int x, int y ) { int max; if ( x > y ) max = x; else max = y; cout << "\nThe maximum value : " << max; } void minimum ( int x, int y ) { int min; if ( x < y ) min = x; else min = y; cout << "\nThe minimum value : " << min; }
97
Exercise
1. Given floating-point values for a, b and c, find the values of x where x = -b ± (b2 – 4ac) 2a
2. Write a program that reads a student’s name together with his or her test
scores. The program should then compute the average test score for each
student amnd assign the appropriate grade. The grade scale is as follows: 90
