Foundations Updated 2026-09 View as Markdown

While loops

While loops are similar to for loops, but have less functionality.

While loops are similar to for loops, but have less functionality. A while loop continues executing the while block as long as the condition in the while remains true. For example, the following code will execute exactly ten times:

int n = 0;
while (n < 10) {
    n++;
}

While loops can also execute infinitely if a condition is given which always evaluates as true (non-zero):

while (1) {
   /* do something */
}

Loop directives#

There are two important loop directives that are used in conjunction with all loop types in C - the break and continue directives.

The break directive halts a loop after ten loops, even though the while loop never finishes:

int n = 0;
while (1) {
    n++;
    if (n == 10) {
        break;
    }
}

In the following code, the continue directive causes the printf command to be skipped, so that only even numbers are printed out:

int n = 0;
while (n < 10) {
    n++;

    /* check that n is odd */
    if (n % 2 == 1) {
        /* go back to the start of the while block */
        continue;
    }

    /* we reach this code only if n is even */
    printf("The number %d is even.\n", n);
}

7
5
9
5

#include <stdio.h>

int main() {
    int array[] = {1, 7, 4, 5, 9, 3, 5, 11, 6, 3, 4};
    int i = 0;

    while (i < 10) {
        if(array[i] < 5){
            i++;
            continue;
        }

        if(array[i] > 10){
            break;
        }

        printf("%d\n", array[i]);
        i++;
    }

    return 0;
}