Prof. Amr Goneid, AUC 1

CSCE 110PROGRAMMING FUNDAMENTALS

WITH C++

Prof. Amr GoneidAUC

Part 2. Overview of C++

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Overview of C++

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Overview of C++

HistoricalC++ Basics Some Library Functions Expressions & Assignment Simple Input/Output

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Historical 1967: BCP language (Martin Richards,

Cambridge) 1969: B language (Ken Thompson, Bell labs) Early 1970’s: C language & Unix Operating

System (Dennis Ritchie, Bell Labs)

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Historical Mid-1980’s: Early C++ derived from C

(Bjarne Stroustrup, Bell labs) 1998: Formally standardized C++, an OOP

language

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1. C++ Basics

Example Program Style, DeclarationsData TypesConstantsDeclaring Constants & variables

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1.1 Example Program:Sorting an Array of Integers

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Sorting an Array of Integers# include <iostream>using namespace std;

// Functions Usedvoid selectsort (int a[ ] , int n); // Function Prototype

int main() // Start of main function {

const int MAX = 100; // Data Declarationsint a[MAX], k, n;

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Example Program:Main Function Actions

/* Begin Main Actions */cin >> n; // Read size of data if (n > MAX) n = MAX; // to prevent array overflowfor (k = 0; k < n; k++) cin >> a[k];

// Read data into array selectsort(a,n); // Call sorting module for (k = 0; k < n; k++) cout << a[k];

// Write sorted data cout << ‘ \n ’ // Move to a new linereturn 0; // No errors

} /* End. Main Function */

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Example Program:Sorting Module (Function)void selectsort (int a[ ], int n)

{ // Begin Moduleint i, j, min, temp; // Module Local Data for (i = 0; i < n-1; i++ ) // Begin module action {

min = i;for ( j = i+1; j < n; j++)

if (a[j] < a[min] ) min = j;temp = a[min]; a[min] = a[i]; a[i] = temp;

}} // End Module

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1.2 Style

Lines Separators (spaces, lines, comments) Comments ( //.. Single line or /*..*/ ) Case sensitive ( e.g. MAX, max) Keywords ( e.g. for if return ..)

use lowercase letters User Identifiers (e.g. MAX, min, a, n,

selectsort,.. etc)

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Style (continued)

Constants (e.g. MAX ,100 , ‘\n’ etc) Operators (e.g. <= ++ + >> etc) Punctuators (e.g. ( ) ; { } etc) Keywords, identifiers, constants,

operators and punctuators are called TOKENS

Compiler Directives

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Compiler Directives

#include Compiler directive Processed at compilation time Instructs compiler on what you want in the

program #include <iostream>

Adds library files to program Used with < > Also “ “ user defined

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Some Declaration Keywords

Modules (Functions):main() void <function name>(..)

Data Declaration:const for constant dataint , float , etc, for data typesstring for user defined strings

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1.3 A Classification of Data Types

Data Type

Scalar Data Structure

IntegerFloatingCharacter

Logical(bool)

Pointer ArraysStructsUnionsClasses

FilesStreamsstrings……..

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Some Scalar Data Types

Integers:int short unsigned int long

Floating:float double long double

Character:char unsigned char

Logical (Boolean):bool

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Ranges of Scalar Data Types

int , short 2 bytes -32,768 .. 32,767 unsigned int , unsigned short 2 bytes

0 .. 65,535 long 4 bytes -2G .. 2G unsigned long 4 bytes 0 .. 4G float 4 bytes ~ E +/- 38 (7 digits) double 8 bytes ~ E +/- 308 (15 digits) long double 10 bytes ~ E +/- 4932 (19 digits)

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Ranges of Scalar Data Types

char 1 byte -128 .. 127 unsigned char 1 byte 0 .. 255 bool 1 byte true / false

non-zero / zeroNote:Integer , character and boolean types are

called Ordinal Types because their members can be listed by rank.

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1.4 Examples of Constants Predefined:

true false SHRT_MAX (32767) Integer:

79 (decimal of type int)232467L (decimal of type long)

Floating:1.35 2.34e-3 5.705E+5 (decimal of type double)

Character: ‘A’ ‘\n’ (type char) String Literals: “Hello” (class string)

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1.5 Declaring & Initializing Constants Syntax : const <type> <name> = <value>; Examples:

const int MAX = 100; {integer}const bool says = true; {Boolean}const string message = “warning!”;

{String literal}const float KmperMile= 1.609344F; {float}const alpha = 1.2345E-15; {double}const Large = -2345678L; {long}const char Initial = ‘H’; {char}

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Declaring & Initializing Variables Syntax: <type> <name>, <name> .. ;

or <type> <name> = <value>; Examples:

unsigned char pixel ;int k = 2197;float x , y ;char c ;bool test ;string name = “Ann W. Wolf”;

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Assigning Constants to Variableschanges initial values Examples:

pixel = 212;k = -16329;x = 3.1415926;c = ‘H’;test = false;name = “John W. Wolf ”;k = SHRT_MAX;

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2. Some Library Functions

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Some Library Functions

To invoke: FunctionName (x)returns value of function for argument x

Examples:char(65) returns ‘A’int(‘A’) returns 65sqrt(4) returns 2.0abs(-6) returns 6sin(1.5708) returns 1.00

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Library Functions(continued)cos(0.0) returns 1.0atan(1.0) returns pi/4tan(0.0) returns 0.0log(2.0) returns 0.693147exp(2.0) returns 7.38906pow(4,1.5) returns 8.00 = 41.5

ceil(2.67) returns 3.0floor(2.67) returns 2.0Random(n) returns random int 0 .. n-1

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Using a Library Function

//Computes w = (1+z)2.6 z 1.45 / (1-z)3.2

# include <cmath> // pow function# include <iostream> // I/O functionsusing namespace std;

int main ( ){

float w , z ;cout << “Enter z: “ ; cin >> z ;w = pow(1+z,2.6) * pow(z,1.45) / pow(1-z,3.2);cout << “Value of w = “ << w << endl;return 0 ;

}

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3. Expressions & Assignment

Syntax Arithmetic Expressions Logical Expressions Relational Expressions Assignment Statement Overall Operator Precedence More on Arithmetic and Assignment

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3.1 Syntax

Form1 Form2

e.g -5 a + b!found x > y+ 32 (c >= 65) && (c <=90)

U-Op operand B-Opoperand operand

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Syntax Operands:Constants e.g. 5 false Variables e.g. x a[3] Functions e.g. sqrt(7) sin(y) Expression e.g. x + y a > b

Operators:Arithmetic Logical Relational AssignmentCompound

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3.2 Arithmetic Expressions

Operators:Unary Minus and Plus (-) (+)Multiplication, Division, Modulus

( * / % )Addition, Subtraction ( + - )

Examples:-5 a*b sqrt(5)/2.0 x % m y - b (a+sqrt(y))/(6- sin(pi*y)) m / n - k

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Arithmetic Expressions

Examples:5 / 2 is 2 (int operands, int value)5.0 / 2.0 (float operands, float value)5.0 / 2 (Mixed operands, float value)7 % 2 is 1 3 % 5 is 3 (% for int only)2 + 6 /3 + 5 is 9 but (2 + 6) / (3 + 5) is 1

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Arithmetic Expressions

Operator Precedence:( ) Highestunary + -* / %Add (+) , Subtract (-) Lowest

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Example

How many Hours, Minutes, Seconds are in n seconds?

int n, hrs, mins, secs, rem;hrs = n / 3600;rem = n % 3600;mins = rem / 60;secs = rem % 60;

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3.3 Logical Expressions

Operators:! (unary not) || (or) && (and)

Operands of Boolean typeResult: Boolean ( true , false ) Examples:

! true is false a || b ! (x<y)c && d

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Truth Table for Logical Operators0 false , 1 true

x y !x x || y x && y

0 0 1 0 00 1 1 1 01 0 0 1 01 1 0 1 1

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3.4 Relational Expressions

Operators:== < > <= >= !=

Result: Boolean Examples:

a > b c <= 6 sqrt(x) >= yz != w a+b == c+d ‘A’ < ‘a’name1 != name2

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The Assignment operator ( = ) Syntax: variable = expression; Examples:

int x , y ; bool a,b,c ;x = 3; y = 2*x; a = true;a = x > y; c = a || b;

3.5 Assignment Statement

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3.6 Overall Operator Precedence Parentheses ( ) Highest Unary: ! + - Multiplicative: * / % Additive: + - Relational: < > <= >= Relational: == != Logical: && Logical: || Assignment = Lowest Example:

d = !(x+y < z) && (2*b == c);

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3.7 More on Arithmetic and Assignment Increment and Decrement Operators:

++operand --operand(increment/decrement operand then evaluate expression)operand++ operand--(evaluate expression then increment/decrement operand )e.g. n++ , ++n is shorthand for n = n + 1

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Increment and Decrement Operators Examples:

int a = 3; int b = 5; int c; c = a + b++; yields a == 3, b == 6, c == 8 c = a + ++b; yields a == 3, b == 6, c == 9 c = a + b--; yields a == 3, b == 4, c == 8 c = a + --b; yields a == 3, b == 4, c == 7

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Multiple & Compound Assignment Multiple Assignment:

c = a = b; d = (a = b + 3) / c; Compound Assignment:

(Reassign after doing operation)e.g. a = a + b; //var = var op expr;can be written:a += b; //var compound-op expr;

compound operators += -= *= /= %=e.g. c /= (x + 2); is c = c / (x + 2);

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4. Simple Input/Output

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Simple Input/Output

Standard I/O Devices:cin standard input stream (keyboard)cout standard output stream (screen)Defined in #include <iostream>

Extraction Operator:>> DataVariableextracts one data item from cin to a variable

Insertion Operator:<< DataElementinserts one data element in cout

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Simple Input/Output

Keyboard Input:cin >> v ;cin >> v1 >> v2…;

Variables are entered with spaces between them. ENTER or RETURN end input.

e.g. int a,b; float x; string name;cin >> name; cin >> a >> b >> x;

A.W.Wolf12 524 2.567

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Data Types and cin

Don’t mix types with cinint x;cin >> x;

If Keyboard input is16.6The value placed in x would be 16

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Other Characteristics of cin

Leading blanks ignored (floats, int, char, bool and strings)

Char read 1 at a time (1 non blank)Case issues int or float will read until space Stings same as int and float

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Simple Input/Output

Screen Output:cout << d; cout << d1 << d2 ..;

Examples:int a,b,c; float z;cout << “Enter a,b,c: “; Enter a,b,c: 600 2 500cin >> a >> b >> c;cout << a << 2*b << endl; 6004z = sqrt(a + b * c);cout << “Result is “;cout << z; Result is 40.00

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Example Program : Hello.cpp// FILE: Hello.cpp// DISPLAYS A USER'S NAME

#include <iostream>#include <string>

using namespace std;

int main (){

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Hello.cppchar letter1, letter2;string lastName;

// Enter letters and print message.cout << "Enter 2 initials and last name: ";cin >> letter1 >> letter2 >> lastName;cout << "Hello " << letter1 << ". " <<

letter2 << ". " << lastName << "! ";cout << "We hope you enjoy studying C++." <<

endl;return 0;

}

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Hello.cpp

Program Input/output

Enter 2 initials and last name: SAWolf

Hello S. A. Wolf! We hope you enjoystudying C++.