定义一个栈，并实现栈的基本操作：

void Push( const T& x) //

bool Pop(T& x) //

bool getTop(T& x) const //

ostream& operater<<(ostream& os, Stack<T>& s) //overload

-The definition of a stack, and to achieve the basic operation of the stack: void Push (const T &　x) // bool Pop (T &　x) // bool getTop (T &　x) const // ostream &　operater < < (ostream &　os, Stack <T> &　S) // overload