What is control loop?

Answer 1

An exit-controlled loop is a loop where the controlling conditional expression is evaluated at the end of each iteration, as opposed to an entry-controlled loop where the expression is evaluated at the beginning of each iteration. The upshot is that an exit-controlled loop always executes at least one complete iteration whereas an entry-controlled loop might not iterate at all:

int x = 100;

// entry-controlled loop

while (x<50) { printf ("%d\n", x++); // won't execute at all because x<50 is false }

// exit-controlled loop

do {

printf ("%d\n", x++); // will execute one time only

} while (x<50);