The while loop in c is an entry controlled loop (Entry Controlled Loops are used when checking of a test condition is mandatory before executing the loop body). It is generally used where we don’t know the number of iterations.

Syntax of while loop in C:

initialization;
while(condition)
{
   //code to be executed
   updation;
}

Example:

 
#include <stdio.h>

int main() {
   int n,sum=0;
   scanf("\n%d",&n);
    int temp=n;
    while(temp>=1)
    {
       sum=sum+temp;
        temp--;
    }
     printf("%d",sum);
    return 0;
}

output:

5
15

Here, we are calculating the sum of n natural numbers using the while loop.

Infinite while loop in c:

while(1){  
//statement  
}

If the expression passed in the while loop results in any non-zero value, then the loop will run an infinite number of times.

key points about while loop:

• The statements within the while loop would keep on getting executed till the condition being tested remains true.
• The condition being tested may use relational or logical operators.
• The statement within the loop may be a single line or a block of statements.
• It is not necessary that a loop counter must only be an int. It can even be a float.
• In a while loop, the condition expression is compulsory.
• Running a while loop without a body is possible.
• There can be more than one conditional expression in the while loop.

Note: also read about  Loops in C & Loops and its examples

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Rabecca Fatima

Staying up to the mark is what defines me. Hi all! I’m Rabecca Fatima a keen learner, great enthusiast, ready to take new challenges as stepping stones towards flying colors.