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Working with the Stack Type

The System.Collections.Stack type represents a collection that maintains items using a last-in,

first-out manner. As you would expect, Stack defines a member named Push() and Pop() (to place

items onto or remove items from the stack). The following stack example makes use of the standard

System.String:

static void StackTest()

{

Console.WriteLine("\n=> Stack Test:\n");

Stack stringStack = new Stack();

stringStack.Push("One");

stringStack.Push("Two");

stringStack.Push("Three");

// Now look at the top item, pop it, and look again.

Console.WriteLine("Top item is: {0}", stringStack.Peek());

Console.WriteLine("Popped off {0}", stringStack.Pop());

Console.WriteLine("Top item is: {0}", stringStack.Peek());

Console.WriteLine("Popped off {0}", stringStack.Pop());

Console.WriteLine("Top item is: {0}", stringStack.Peek());

Console.WriteLine("Popped off {0}", stringStack.Pop());

try

{

Console.WriteLine("Top item is: {0}", stringStack.Peek());

Console.WriteLine("Popped off {0}", stringStack.Pop());

}

catch(Exception e)

{ Console.WriteLine("Error!! {0}", e.Message);}

}

Here, you build a stack that contains three string types (named according to their order of

insertion). As you peek into the stack, you will always see the item at the very top, and therefore the

first call to Peek() reveals the third string. After a series of Pop() and Peek() calls, the stack is eventu-

ally empty, at which time additional Peek()/Pop() calls raise a system exception.