Intro to Programming

(1)

Intro to Programming Week # 2

Variables/Data type Lecture # 4 & 5

By: Saqib Rasheed

Department of Computer Science & Engineering Air University

(2)

// First Program

// Author Saqib Rasheed

#include <iostream>

using namespace std;

int main() {

cout << "Hello world!";

return 0;

}

A First Program - Greeting.cpp

(3)

Greeting Output

By Saqib Rasheed 3

(4)

Whitespace

#include <iostream>

using

namespace std;

int main () { cout

<<

“Hello word!\n”

; return

0;}

(5)

• Reference Chapter # 2:

C++ Programming Basics by Robert Lafore

By Saqib Rasheed 5

(6)

Escape Sequence

• Escape sequences are used to represent certain special characters within string

literals and character literals.

• \n new line

• \t horizontal tab (8 spaces)

• \’ single quote

• \” double quote

• \? question mark

• \v vertical tab

• \a audible bell

(7)

Example # 2

#include <iostream>

using namespace std;

int main ( ) {

cout << “\t Welcome to Air University \n“;

cout<<“ \n\t School of Engineering”;

cout<<“it can be\n used \t between\n the string”;

return 0;

}

New Line Tab

By Saqib Rasheed 7

(8)

Variables

• A storage box, its type defines the kind of stuff you store in it

– E.g. shoe box  used for shoes

– Jewelry box  used for jewelry

– CD kit  used for CDs

(9)

Variable

• Variable is a box

• In computer, a storage box is a memory location on RAM

By Saqib Rasheed 9

(10)

Memory in Computer

• First you ask computer to give you a box and you also have to specify what type of box you want

Occupied Memory Spaces

Free Memory Spaces

Each little box is a memory

location

(11)

Asking for Memory

Type of Box box name;

Type is a bit

messy, it can’t be shoe box or

jewelry

Could be anything, alpha, bravo, charlie

integer character double float

bool (etc)

Some rules apply 

By Saqib Rasheed 11

(12)

Rules for Variable name

Rules to Write Variable.

1. First Letter is always Character

2. Underscore _ (Not Recommended) 3. Can’t use real numbers (Syntax Errorr) int num1;

(13)

Rules for Variable name

In a program a variable has:

1. Name 2. Type 3. Size 4. Value

int num = 10;

Assignment Operator

By Saqib Rasheed 13

(14)

Rules of variables

• int n1;

• int n1,n2,n3;

• int n1; int n2; int n3;

• float a1; int b1; double c1;

(15)

Type Size (bytes) Range-Minimum Range- Maximum

 Character 1 -128 127

Unsigned Char 1 0 255 Signed Char 1 -128 127

Integer 4 -2,147,483,648 2,147,483,647 Signed Int 4 0 ,4294,967,295

Unsigned Int 4 -2,147,483,648 2,147,483,647 Short Int 2 -32,768 32,767

Signed short Int 2 0 65,535

Unsigned Short Int 2 -32,768 32,767

Long Int 4 -2,147,483,648 2,147,483,647 Signed Long Int 8 0 4,294,967,295

Unsigned Long Int 8 -2,147,483,648 2,147,483,647 Float 4 1.8E-38 3.4E+38

Double 8 2.2E-308 1.8E+308 Long Double 8 2.2E-308 1.8E+308

Bool 1 True/False

By Saqib Rasheed 15

(16)

How To get Value from User

How to get value from user we use

cin>>x;

Also defined in <iostream> library file

16

(17)

Displaying age

#include<iostream>

using namespace std;

int main (){

float a1,a2;

cout<<“Enter age for student 1=”;

cin>>a1;

cin>>a2;

cout<<a1;

cout<<a2;

return 0;

} By Saqib Rasheed 17

(18)

Displaying age

#include<iostream>

int main (){

float a1,a2;

cin>>a1;

cin>>a2;

cout<<“\nAge of Student 1 = ”<<a1;

return 0;

(19)

Displaying age

#include<iostream>

int main (){

float a1,a2;

cin>>a1;

cin>>a2;

cout<<“\nAge of Student 2 = “ <<a2;

return 0;

} By Saqib Rasheed 19

(20)

Displaying age

#include<iostream>

int main (){

float a1,a2;

cin>>a1;

cin>>a2;

cout<<“\nAge of Student 2 = “;

cout <<a2;

return 0;

(21)

Average age Example

#include<iostream>

int main (){

float a1,a2,a3,a4,a5;

cin>>a1;

cin>>a2;

: :

float sum, avg;

sum = a1+a2+a3+a4+a5;

Avg = sum / 5;

cout<<“Average age = ”<<avg;

return 0;

}

By Saqib Rasheed 21

(22)

Arithmetic Operators

• Common

– Addition + – Subtraction - – Multiplication * – Division /

– Mod %

• Note

– No exponentiation operator – Single division operator

– Operators are overloaded to work with more than one type of object

Write m*x + b not mx + b

(23)

Integer Division

• Integer division produces an integer result

– Truncates the result

• Examples

– 3 / 2 evaluates to 1 – 4 / 6 evaluates to 0 – 10 / 3 evaluates to 3

By Saqib Rasheed 23

(24)

Mod

• Produces the remainder of the division

• Examples

– 5 % 2 evaluates to 1 – 12 % 4 evaluates to 0 – 4 % 5 evaluates to 4

(25)

Operators and Precedence

• Consider mx + b

Consider m*x + b which of the following is it equivalent to

 (m * x) + b

 m * (x + b)

Operator precedence tells how to evaluate expressions

Standard precedence order

 () Evaluate first, if nested innermost done first

 * / % Evaluate second. If there are several, then evaluate from left-to-right

 + - Evaluate third. If there are several, then evaluate from left-to-right

By Saqib Rasheed 25

(26)

Operator Precedence

• Examples

**20 - 4 / 5 * 2 + 3 * 5 % 4**

(4 / 5)

((4 / 5) * 2)

((4 / 5) * 2) (3 * 5)

((4 / 5) * 2) ((3 * 5) % 4) (20 -((4 / 5) * 2)) ((3 * 5) % 4) (20 -((4 / 5) * 2)) + ((3 * 5) % 4)

(27)

27 By Saqib Rasheed

Precedence

21.2 192 19.2

24 8

**X = 2 + 4 * 6 ( 10 – 2 ) / 10 Y = 10 / 5 * 2 ( 8 - 2 ) + 6**

Write Code for this equation

12 3

5

(28)

Quadratic Equation

• In algebra

y = ax² + bx + c

• In C

y = a_*x_*x + b_*x + c

(29)

29 By Saqib Rasheed

using namespace std int main ( ) {

int x ; int y ; int z ; x = 10 ; y = 20 ; z = x + y ;

cout << " x = " ; cout << x ;

cout<< " Y = " <<y;

cout << " z =x + y " << x+y ; }

(30)

• int x, y, z ;

• int x; int y; int z ;

• char n1, n2 = ‘a’;

• float num1, num2 = 30.8, n3;

• double n3;

Declaration of Variables

(31)

Calculator Code

using namespace std int main ( ) {

int num1, num2, res;

cout<<“Enter Number 1 =”;

cin>>num1;

cout<<“Enter Number 2 =”;

cin>>num2;

res = num1 + num2;

cout<<“Addition Result = ”<<res;

res = num1 - num2;

cout<<“Subtraction Result = ”<<res;

res = num1 * num2;

cout<<“Multiplication Result = ”<<res;

res = num1 / num2;

cout<<“Division Result = ”<<res;

res = num1 % num2;

cout<<“Modulation Result = ”<<res;

} ³¹

(32)

Assignment # 1

• Get five equations and write code for each equation

– The depth of equation should be at least 6 numbers – Get these numbers from user (Key board)

– Display the equation properly (Before ) – Display the Result

• Instructions

– Individual assignment – Due date is next class

– Copied assignments will be marked zero – Late assignments not accepted

– Submit hard copies along with out put (Screen Shots)

(33)

• Reference Chapter # 2:

C++ Programming Basics by Robert Lafore

• https://sites.google.com/site/saqibrashied/cplusplus

By Saqib Rasheed 33