Keep going until the limit

The program needs to print each available space until it reaches the limit. A while loop checks its condition before every pass, so a false starting condition skips the body entirely. Compared with for, the setup usually sits before the loop and the update inside it. This form is handy when the stopping condition matters more than a fixed number of passes.

In the diagram, a count of 0 passes count < 3; at 3, the condition fails. Look for the statement that changes the count, or the loop might never stop.

Run the space labels:

#include <stdio.h>

int main(void) {
    int space = 1;
    while (space <= 3) {
        printf("Space %d\n", space);
        space = space + 1;
    }
    printf("Done\n");
    return 0;
}

Start space at 4 for one run. The body is skipped; only Done appears. A loop can also jump by more than one each time. This one doubles its width:

#include <stdio.h>

int main(void) {
    int width = 2;
    while (width < 10) {
        printf("Width: %d\n", width);
        width = width * 2;
    }
    printf("Width limit reached\n");
    return 0;
}

The checks see 2, 4, 8, and 16. Only the first three print: 16 fails width < 10. Before writing a new while loop, identify both its stop condition and the update that moves toward it. The countdown exercise uses a decreasing value instead.