链式栈的C++实现

这是去年的内容，之前放在github的一个被遗忘的reporsity里面，今天看到了就拿出来

#include<iostream>
#include<string>
using namespace std;
/*
question#1;栈的链式存储
goal:数据结构的建立、元素插入、删除等基本操作。
解释实现过程，演示实现例子以及运行结果。
*/
template <typename Type> class LinkStack;//the definition of template
template<typename Type> class LinkStackNode
{
	friend class LinkStack<Type>;//the definition of friend class ,so the class LinkStack can use the private element of class LinkStack
public:
	LinkStackNode(Type &e, LinkStackNode<Type> *p = NULL) :elem(e), next(p) {};
private:
	Type elem;
	LinkStackNode<Type>*next;//it points to the next element
};
template<typename Type>class LinkStack {
public:
	LinkStack() :top(NULL) {};//the initialization of LinkStack
	~LinkStack();
	int IsEmpty()const { return top == NULL; }
	void LinkStackClear();
	int LinkStackLength()const;
	Type GetTop();
	void Push(Type &e);
	Type Pop();
private:
	LinkStackNode<Type>*top;
};
template <typename Type>//the template must be redefinited whenever it is used once
LinkStack<Type>::~LinkStack()
{
	LinkStackNode<Type> *p;
	while (top != NULL)
	{
		p = top;
		top = top->next;
		delete p;
	}
};
//all methods are defined out of the class
template <typename Type>
void LinkStack<Type>::Push(Type &e)//Enter the LinkStack
{
	LinkStackNode<Type>* p;
	p = new LinkStackNode<Type>(e, top);
	if (p == NULL)
	{
		cout << "	The space distribution of LinkStackNode falls!" << endl;
		return;
	}
	top = p;
};
template <typename Type>
Type LinkStack<Type>::Pop()
{
	if (LinkStack::IsEmpty())
	{
		cout << "The LinkStack is empty!" << endl;
		return 0;
	}
	LinkStackNode<Type> *p = top;
	top = top->next;
	Type q = p->elem;
	delete p;
	return q;
};
template <typename Type>
Type LinkStack<Type>::GetTop()
{
	if (LinkStack::IsEmpty())
	{
		cout << "The LinkStack is empty!" << endl;
		return 0;
	}
	return LinkStack::top->elem;
};
template <typename Type>
int LinkStack<Type>::LinkStackLength()const
{
	LinkStackNode<Type>*p = top;
	int i = 0;
	while (p) { i++; p = p->next; }
	return i;
};
template <typename Type>
void LinkStack<Type>::LinkStackClear()
{
	LinkStackNode<Type>* p;
	while (top->next != NULL)
	{
		p = top;
		top = top->next;
		delete p;
	}
};
int main()
{
	string a = "aspect";
	LinkStack<string>temp;//Pay attention here!You can only create objections instead of new classes by this.
	temp.Push(a);
	cout << temp.GetTop() << endl;
	cout << temp.LinkStackLength() << endl;
	cout << temp.Pop() << endl;
	temp.Pop()
	return 0;
}