The do-while loop is the cousin of while with one twist: it checks the condition after the body runs. That means the body always executes at least once.
The do-while Loop
Write do, then the body, then while (condition). The semicolon at the end is required — don't forget it.
#include <stdio.h>
int main() {
int i = 1;
do {
printf("Count: %d\n", i);
i++;
} while (i <= 5);
return 0;
}
Guaranteed Execution
Even if the condition is false from the start, the body still runs once. This is handy when you need something to happen before you check — like showing a menu or reading input.
#include <stdio.h>
int main() {
int i = 10;
do {
printf("This runs once even though %d > 5\n", i);
i++;
} while (i <= 5);
return 0;
}
while vs do-while
Use while when you might not need to run the body at all. Use do-while when the body must run at least once regardless of the condition.