a.h

it can help you use C++ program we

//类A、B和C的定义及实现
#include <iostream>
using namespace std;
class A
{
protected:
	int		type;		// 说明该类的类型，如果是A，那么type = 0
public:
	A() {  type = 0;  }
	void Display()
	{
		cout << "A::Display()\n";
	}
	int GetType() { return type; }		//返回类型
	void Hello()  { Display();   }
};

class B : public A
{
public:
	B() { type = 1; }	//类为B，所以type = 1
	void Display()
	{
		cout <<"B::Display()\n";
	}
};
class C : public A
{
public: 
	C() { type = 2; }		//类为C，所以type = 2

	void Display() 
	{
		cout <<"C::Display()\n";
	}
};