程序实现双向栈的基本操作：1）初始化；2）判断栈是否为空；3）判断栈是否已满；4）入栈；5）出栈；6）清空栈；7）取栈顶元素。还有几个比较巧妙操作....哦-Realize two-way process stacks the basic steps: 1) initialization　2) to determine whether the stack is empty　3) to determine whether the stack is full　4)入栈　5) a stack　6) Empty the stack　7) from Stack Top element. There are also several relatively subtle operation .... Oh