An instruction or group of instructions.

Computer executes program repeatedly for specified number of times. Or until some terminating conditions are satisfied.

3

What is loop?

2

There are two types of loop.

A. Determinant loop or counter loop:

• Extremely powerful loop.

• This loop is used, when the number of executions or iteration is known.

• Used in programs like print “university of swat” 5 times. Etc.

TYPES OF LOOP:

3

B. Undeterminant loop or controlled loop:

• Its Execution depends upon the condition either true or false.

• The number of iteration is not known before the operation.

• While and do while loops are used here.

TYPES OF LOOP:

There are three methods to loop a program.

A. Using For loop or (For statement).

B. Using while loop or (while statement).

C. Using do while loop or (do while statement).

4

METHODS TO LOOP A PROGRAMME:

5

The popular and mostly used loop.

It is determinant loop.

It checks the condition before execution. Which means that it is pretest loop .

FOR LOOP OR FOR STATEMENT:

6

A. INITIALIZATION: Means to assign value for variable to initialize the loop. i.e (azr=11).

B. CONDITION: Test the condition either it reach the desire number of execution or not. i.e (azr<=20).

C. EXPRESSION UPDATE: It increases the loop counter as much it executes. i.e (azr=11+1).

The “FOR LOOP” specify the following three statements:

7

{ for (azr=11,azr<=20,azr=11+1) expression update

initialization condition

{ Body of the loop } }

The above three operations are written in program as:

8

#include<stdio.h>#include<conio.h> void main ( ){ int azr; clrscr ( ); for(azr=5;azr<=45;azr=5+1) { printf(“%d\n”,azr); } getch(); }

A program in for loop:

9

Then we put “if” statement after the “for” statement. i.e

to get even numbers:{For (initialization ;condition ; expression update) if (azr%2==0); }

to get odd numbers the if statement should be if (azr%2!=0).

To get even integers or odd integers:

10

#include<stdio.h>#include<conio.h>

void main( ) { int amb; clrscr( ); { for (amb=20;amb<=40;amb=amb+1) if (amb%2==0); } printf (“%d\n”,amb);

getch(); }

FOR EXAMPLE: TO GET EVEN NUMBERS ON THE BLACK SCREEN:

11

#include<stdio.h>#include<conio.h>

void main( ) { int X; clrscr( ); { for (X=9;X<=35;X=X+1) if (X%2!=0); } printf (“%d\n”,X);

getch(); }

TO GET ODD NUMBERS: