程序代码：

#include<iostream>
#include<exception>
using namespace std;
template<class Type>
struct node
{
    Type key;
    node *next;
    node(Type k):next(NULL){ key=k;}
    node<Type>(node<Type> & n){
        this->key=n->key;
        this->next=n->next;
    }
    ~node(){ next=NULL;}
};

template<class Type>
class stack
{
private:
    size_t Size;
    node<Type> *tail;
    node<Type> *top;
public:
    stack<Type>():top(NULL),tail(NULL),Size(0){}
    void push(Type n){    
        node<Type> *point=new node<Type>(n);
        try
        {
            point->next=top;
            top=point;
        }catch ( exception e)
        {
            
        }
    }
    Type pop()
    {
        node<Type> *tmp;
        Type k;
        try{
            if( tail == top )
            {
                throw exception();
            }
            tmp=top;
            top=top->next;
            k=tmp->key;
            delete tmp;
            return k;
        }catch ( exception e )
        {
            cout<<e.what();
            exit (1);
        }    
    }
    size_t size(){return Size;}
};

int main()
{

    stack<int> st;
    st.push(1);
    st.push(2);
    st.push(3);
    cout<<st.pop()<<endl;
    cout<<st.pop()<<endl;
    cout<<st.pop()<<endl;
    return 0;
}