# ifndef STACK_H
# define STACK_H
# include <iostream.h>
# include <stdlib.h>
# include <assert.h>          //斷言
# include "Stacknode.h"
template <class Type>
class stack
{
public:
	stack():top(NULL){} //構(gòu)造函數(shù)
	~stack();
	void push(const Type &item);              //將數(shù)據(jù)item壓入棧中
	Type pop();                 //取出棧頂?shù)臄?shù)據(jù),同時(shí)top下移一位
	Type gettop();               //取出棧頂?shù)臄?shù)據(jù),top的指向位置不變
	void makeempty();                //將棧清空
	int isempty() const;                        //判斷棧是否為空
private:
	stacknode<Type> *top;        //指向棧頂?shù)闹羔?};


template <class Type>
stack<Type>::~stack()
{
	stacknode<Type> *p;
	while(top!=NULL)            //將棧內(nèi)的結(jié)點(diǎn)逐一刪去
	{
		p=top;
		top=top->link;
	    delete p;
	}
}

template <class Type>
void stack<Type>::push(const Type &item)
{
	top=new stacknode<Type> (item,top);          //數(shù)據(jù)item壓入棧中
}

template <class Type>
Type stack<Type>::pop()
{
	assert(!isempty());            //斷言棧不空
	stacknode<Type> *p=top;
	Type retvalue =p->data;            //取數(shù)據(jù)
	top=top->link;                  //棧頂指針下移一位
	delete p;
	return retvalue;            //返回棧頂?shù)臄?shù)據(jù)
}

template <class Type>
Type stack<Type>::gettop()
{
	assert(!isempty());
	return top->data;           //直接取出棧頂?shù)臄?shù)據(jù)
}

template <class Type>
void stack<Type>::makeempty()
{
	top=NULL;           //直接將棧頂指針指向棧底
}

template <class Type>
int stack<Type>::isempty() const                   //判斷棧是否為空
{
	return top==NULL; 
}


# endif