Lecture 2 - Overriding Member Functions

You can use member functions in a derived class that override—that is, have the same name as those in
the base class. You might want to do this so that calls in your program work the same way for objects of
both base and derived classes. Here’s an example based on the STAKARAY program. This program
models a stack, a simple data storage device. It allows you to push integers onto the stack and pop them
off. However, STAKARAY has a potential flaw. If you tried to push too many items onto the stack, the
program might bomb, since data would be placed in memory beyond the end of the st[] array. Or if you
tried to pop too many items, the results would be meaningless, since you would be reading data from
memory locations outside the array. To cure these defects we’ve created a new class, Stack2, derived
from Stack. Objects of Stack2 behave in exactly the same way as those of Stack, except that you will be
warned if you attempt to push too many items on the stack or if you try to pop an item from an empty
stack.