While Loops

The While loop

A while loop is an event controlled loop. It is a control flow statement that, allow the code to be executed repeatedly based on a given condition.

To while construct consists of a block of code and a condition. The condition is evaluated and if the condition is true, the code within the block is executed. This repeats until the condition becomes false.

EXAMPLE 1:

/*Simple while loop that prints numbers 10 per line */

#include<stdio.h> 

int main(void)

{

//local declarations

int num;

int linecount;

//statements

printf("Enter an integer between 1 and 100:");

scanf("%d",&num);  //Initialization 

//Test number

if(num>0)

num=100;

lineCount=0;

while(num>0)

{

if(lineCount<10)

lineCount++;

else

{

printf("\n");

lineCount=1;

} //else

printf("%4d", num--); // num-- updates loop

} //while

return 0;

}

OUTPUT:

Enter an integer between 1 and 100: 15

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

EXAMPLE 2:

/* Add a list of integers from the standard input unit */

#include<stdio.h>

int main(void)

{

//local declarations

int x;

int sum=0;

//statements

printf("enter your numbers: <EOF> to stop.\n");

while(scanf("%d",&x)!=EOF)

sum+=x;

printf("\n The total is: %d\n",sum);

return 0;

} //end main

Output:

Enter your number: <EOF> to stop

15

22

3^d

The total is: 40