Learning C#

Stacks

A stack is a last-in, first-out (LIFO) collection, like a stack of dishes at a buffet table or a stack of coins on your desk. You add a dish on top, and that is the first dish you take off the stack.

Tip

The classic example of a stack is the stack, which is the portion of memory on which parameters and local variables are stored. See Chapter 8 for more about the stack.

The principal methods for adding to and removing from an instance of the Stack class are Push() and Pop(); Stack also offers a Peek() method, very much like Queue. Table 16-5 shows the most important methods and properties for Stack.

Table 16-5. Stack members

Method or Property	Purpose
Count	Public property that gets the number of elements in the Stack
Clear()	Method that removes all objects from the Stack
Contains()	Method that determines if an element is in the Stack
CopyTo()	Method that copies the Stack elements to an existing one-dimensional array
GetEnumerator()	Method that returns an enumerator for the Stack
Peek()	Method that returns the object at the top of the Stack without removing it
Pop()	Method that removes and returns the object at the top of the Stack
Push()	Method that inserts an object at the top of the Stack
ToArray()	Method that copies the elements to a new array

In Example 16-4, you rewrite Example 16-3 to use a Stack rather than a Queue. The logic is almost identical. The key difference is that a Stack is Last In, First Out, while a Queue is First ...