vector实现栈（多多指教）

#pragma once

#define FAIL -1
#include <vector>
using namespace std;
class Stack
{
public:
Stack(void);
int PopS();
void InS(int data);
int GetS() const;
bool Empty() const;
~Stack(void);
private:
vector<int> a;
int top;

};

#include "StdAfx.h"
#include "Stack.h"
#include <iostream>
using namespace std;

Stack::Stack(void)
{
top = -1;
}