While Loops:

While Loops:

Here's the syntax:



while (some "condition" is true)
{
    do something
    update the "condition"
}

For example:


#include <stdio.h>

void main( )
{
  	int counter, limit;
  	counter = 0;
  	limit = 10;
 
  	while (counter < limit)
  	{
    		printf("Counter = %d\n", counter);
    		counter++;
  	}
  	printf("\nOut of the loop!\n");
}

Here's the output:

UNIX prompt >>a.out

Counter = 0

Counter = 1

Counter = 2

Counter = 3

Counter = 4

Counter = 5

Counter = 6

Counter = 7

Counter = 8

Counter = 9

Out of the loop!

Here's how the loop executes:

counter = 0
limit = 10
Is counter < limit ?
Yes, it is!
Execute the printf statement
Increment counter by one [counter++ ==> counter = counter + 1]
Now, counter = 1
limit = 10
Is counter < limit ?
Yes, it is!
Execute the printf statement
Increment counter by one
Now, counter = 2
limit = 10
Is counter < limit?
Yes, it is!
Execute printf statement
Increment counter by one
Now, counter = 3
limit = 10
Is counter < limit?
Yes, it is!
Execute printf statement
Increment counter by one
Now, counter = 4
limit = 10
Is counter < limit?
Yes, it is!
…
…
…
Now, counter = 9
limit = 10
Is counter < limit?
Yes, it is!
Execute the printf statement
Increment counter by one
Now, counter = 10
limit = 10
Is counter < limit?
No, it is not!!
Fall out of the loop without executing the printf statement!!

Note:

2 differences between FOR and WHILE loops:

WHILE loops don't initialize the counter variable; has to be done before the WHILE loop.
WHILE loops don't increment the counter variable; has to be done within the WHILE loop.

#include <stdio.h> void main( ) { int counter, limit; counter = 0; limit = 10; while (counter < limit) { printf("Counter = %d\n", counter); counter++; } printf("\nOut of the loop!\n"); }