#include <assert.h>
#include "Vstack.h"
template<class T>
    class Array_stack : public Gstack<T> {
    	int sz;
    	int top;
    	T* astack;
    public:
    	Array_stack(int Nitems )
    		{ sz = Nitems; astack = new T[sz]; top = sz; }
    	Array_stack( )
    		{ sz = 100; astack = new T[sz]; top = sz; }
    	~Array_stack() 
		    { delete[] astack; }
    	void push(T x) 
		    { assert( !isfull() ); astack[--top] = x; }
    	T pop() 
		    { assert( !isempty() ); return( astack[top++] ); }
    	bool isempty() 
		    { return( top == sz ); }
    	bool isfull() 
		    { return( top == 0 ); }
    };