数组集合篇－Stack类的使用

        Stack（堆栈）类：实现了一个后入先出的机制。元素在顶部进入堆栈（push或入栈操作。），也从顶部离开堆栈（pop或者出栈操作）。

        一个盘子的故事：一叠盘子，后来的盘子总是放在最上面。用盘子的时候，也是从这叠盘子顶部取盘子。最后来的盘子，最先被用了。

using System;
using System.Collections;
............

Stack numbers = new Stack();
//填充堆栈
foreach (int number in new int[4]{9,3,7,2})
{
 numbers.Push(number);
 Console.WriteLine(number + "has been pushed on the stack");
}
.............
//遍历堆栈
foreach (int number in numbers)
{
 Console.WriteLine(number);
}
.............
//清空堆栈
while (numbers.Count!=0)
{
 int number = (int)numbers.Pop();
 Console.WriteLine(number + "has been popped off the stack");
}

输出的结果：
9 has been pushed on the stack
3 has been pushed on the stack
7 has been pushed on the stack
2 has been pushed on the stack
2
7
3
9
2 has been popped off the stack
7 has been popped off the stack
3 has been popped off the stack
9 has been popped off the stack