UMBC CS 201, Fall 05
A stack is a little harder to define than a queue, since there isn't
a common term that will relate how a stack works. It is definitely a linear
collection of similar items. Stacks have access rules too, but the rules are
different than the rules for queues.
You have been exposed to the idea of a stack before. When you go to a
cafeteria to get lunch you take a tray from the stack of trays. You must
always take the tray that is on the top of the stack. The cafeteria personnel
put clean trays on the stack. The clean trays are always added to the top of
the stack, so the tray that's on top is the last one that was added.
A stack is refered to as a LIFO data structure: Last In, First Out.
The Stack ADT
A stack is a linear collection of similar items, where an item to be
added to the stack must be placed on top of the stack and items that are
removed from the stack must be removed from the top. The top of the stack
is known as the top. The term push means to add an item to the
stack, and the term pop means to remove an item from the stack.
There are actually very few operations on a stack.
- Push - add an item to the stack
- Pop - remove an item from the stack
- IsEmpty - is this an empty stack ?
- PrintStack - print the contents of the stack
Thursday, 29-Sep-2005 00:00:51 EDT