Application: Menu driven Modular Program
Numerous longer, more involved programs which have interaction with the user are menu-driven, that means that the program prints a menu of choices and then continues to loop to print the menu of choices until the user selects to end the program. A modular menu-driven program usually would have a function which presents the menu and gets the user's choice, and also functions to implement the action for each selection. Such functions may have subfunctions. The functions would also error-check the entire user input.