链栈类

/*链栈*/#include <iostream>#include <cstdio>using namespace std;template <class T>class LinkStack;template <class T>class Node{    private:        friend class LinkStack<T>;        Node<T> *next;        T data;    public:        Node( T d=0,Node<T> *n=NULL ):data(d),next(n) {}};template <class T>class LinkStack{    private:        Node<T>* top;    public:        LinkStack():top(NULL) {}        ~LinkStack();        bool push( T d );        T gettop();        bool pop();};template <class T>LinkStack<T>::~LinkStack(){    Node<T> *p;    while( top!=NULL )    {        p=top;        top=top->next;        delete p;    }}template <class T>bool LinkStack<T>::push( T d ){    Node<T> *p=new Node<T>( d,top );    top=p;}template <class T>bool LinkStack<T>::pop(){    if( top==NULL ) return false;    top=top->next;}template <class T>T LinkStack<T>::gettop(){    if( top==NULL ) return NULL;    return top->data;}int main(){    LinkStack<char> test;    test.push('a');    test.push('b');    test.push('c');    test.push('d');    while( test.gettop()!=NULL )    {        cout<<test.gettop()<<" ";        test.pop();    }    return 0;}