Flowchart of the Lock Program

You find out if you have used the correct combination only after you have entered all three numbers. Then, if the lock fails to open, you have to try again from the beginning. The flowchart that shows how the lock works.

The flowchart uses a variable correct that is initialy set to true, but is set to false as soon as a wrong number is entered. It is tested after all three numbers have been entered to determine if the lock is to open, or not.