C# 0 The Complete Reference

PART II

C h a p t e r   2 4 :  

C o l l e c t i o n s ,   E n u m e r a t o r s ,   a n d   I t e r a t o r s    

769

    }

  }

}

Here’s the output produced by the program. Notice how the exception handler for 

InvalidOperationException

 manages a stack underflow.

Push(22)

stack: 22

Push(65)

stack: 65 22

Push(91)

stack: 91 65 22

Pop -> 91

stack: 65 22

Pop -> 65

stack: 22

Pop -> 22

stack:

Pop -> Stack empty.

Queue

Another familiar data structure is the queue, which is a first-in, first-out list. That is, the first 

item put in a queue is the first item retrieved. Queues are common in real life. For example, 

lines at a bank or fast-food restaurant are queues. In programming, queues are used to hold 

such things as the currently executing processes in the system, a list of pending database 

transactions, or data packets received over the Internet. They are also often used in 

simulations.

The collection class that supports a queue is called