//5_4.cpp
#include <iostream>
using namespace std;
class Point	//Point類定義
{
public:	//外部接口
	Point(int xx=0, int yy=0) {X=xx; Y=yy; countP++; }	//構(gòu)造函數(shù)
	Point(Point &p);	//拷貝構(gòu)造函數(shù)
	~Point(){  countP--; }
	int GetX() {return X;}
	int GetY() {return Y;}
	void GetC() {cout<<" Object id="<<countP<<endl;}	//輸出靜態(tài)數(shù)據(jù)成員
private:	//私有數(shù)據(jù)成員
	int X,Y;
	static int countP;	//靜態(tài)數(shù)據(jù)成員引用性說明，用于記錄點(diǎn)的個(gè)數(shù)
};
Point::Point(Point &p)
{
	X=p.X;
	Y=p.Y;
	countP++;            //在構(gòu)造函數(shù)中對(duì)countP累加，所有對(duì)象共同維護(hù)同一個(gè)countP
}

int Point::countP=0;                //靜態(tài)數(shù)據(jù)成員定義性說明和初始化，使用類名限定
void main()	//主函數(shù)
{
	Point A(4,5);	//定義對(duì)象A,其構(gòu)造函數(shù)回使countP增1
	cout<<"Point A,"<<A.GetX()<<","<<A.GetY();
	A.GetC();	//輸出對(duì)象個(gè)數(shù)
	Point B(A);	//定義對(duì)象B,其構(gòu)造函數(shù)回使countP增1
	cout<<"Point B,"<<B.GetX()<<","<<B.GetY();
	B.GetC();	//輸出對(duì)象個(gè)數(shù)
}