#include <assert.h>
#include "Lstack.h"

template<class T> 
	Link_stack<T> :: Link_stack(  ) 
    		{ top = NULL; }
template<class T>
	void Link_stack<T> :: push(T x)
    		{ top = new node(x, top); }
template<class T>
	T Link_stack<T> :: pop() {
        		assert( !isempty() );
        		T t = top -> data;
        		node* oldtop = top;
        		top = top -> next;
        		delete oldtop;
        		return t;
    	}
template<class T>
	bool Link_stack<T> :: isempty() 
    		{ return( top == NULL ); }
template<class T>
	bool Link_stack<T> :: isfull() 
    		{ return( FALSE ); }