programming-for-dummies

212
Checking Your Loops
understand as a result (and also harder to fix and update). So when using
loops, keep these points in mind:
✦ To loop a fixed number of times, use a FOR-NEXT loop.
✦ To loop zero or more times, use a WHILE loop.
✦ To loop at least once, use a DO loop.
✦ Both WHILE and DO loops usually need a variable that’s used to check a
Boolean expression to determine when the loop ends.
✦ A WHILE or DO loop always needs a command that changes its Boolean
expression that determines when the loop will eventually stop.
✦ A loop that never stops running is an endless loop.
✦ Some programming languages let you use an EXIT (or break command)
to stop a loop prematurely. Use this with caution because it can make
your program harder to understand.
When using a loop, always make sure you know how that loop will eventually
stop.
Almost every program needs to use loops, so make sure you understand the
differences between all the different loop variations you can use. Ultimately,
loops let you run multiple commands without explicitly writing them all out,
so think of loops as a programming shortcut.