Point.h

/*
 * Point.h
 *
 *  Created on: 2014年5月22日
 *      Author: John
 */
#include<iostream>
using namespace std;
#ifndef POINT_H_
#define POINT_H_


class Point {
private:
int x;
int y;
public:
Point(int x, int y){set(x,y);}
Point():Point(0,0){};
void set(int x, int y){
this->x = x;
this->y = y;
}


Point operator+(const Point &pt);//成员函数，调用该函数的对象成为全局函数
//const关键字，防止输入的参数被修改，&提供对原始数据的引用
friend Point operator-(Point pta, Point ptb); // 可以直接访问 私有属性
friend Point operator-(int n, Point ptb); // 重载操作符


//复制操作符函数
Point &operator=(const Point & src){
set(src.x,src.y);
return *this;//this是指针，对this取值，
//注意到operator前面的&符号 返回的是一个值的引用
}


//输出函数符
friend ostream &operator<<(ostream &outstream, Point &pt);
int get_x() const {return this->x;}
int get_y()const {return this->y;}


virtual ~Point();
};


#endif /* POINT_H_ */

Point.cpp

/*
 * Point.cpp
 *
 *  Created on: 2014年5月22日
 *      Author: John
 */


#include "Point.h"


//Point::Point(int x, int y) {
// // TODO Auto-generated constructor stub
//
//}


Point::~Point() {
// TODO Auto-generated destructor stub
}


Point Point::operator +(const Point &pt){
// Point new_pt;
// new_pt.x =this->x+pt.x;
// new_pt.y = this->y+pt.y;
// return new_pt;


return Point(x+pt.x,y+pt.y); // 这行代码在Point类的内部，所以可以直接访问私有变量。
}

Test.cpp

/*
 * Test.cpp
 *
 *  Created on: 2014年5月22日
 *      Author: John
 */


//#include<iostream>
#include"Point.h"
//using namespace std;


//全局函数的操作符，每个操作数对应于该函数的一个输入参数。
Point operator-(Point pta, Point ptb){
//return Point(pta.get_x()-ptb.get_x(), pta.get_y() - ptb.get_y());
//为了能够直接访问私有变量，可以在Point.h文件里面做如下声明：
//friend Point operator-(Point pta, Point ptb);
return Point(pta.x-ptb.x,pta.y-ptb.y);
}




Point operator-(int n, Point ptb){
return Point(n-ptb.x,n-ptb.y);
}


ostream &operator<<(ostream &outstream, Point &pt){
outstream<<pt.x<<" , "<<pt.y;
return outstream;
}
int main(int argc, char** argv){




Point pt1;
Point pt2(1,2);
Point pt3(3,4);
cout<<"Pt1 is "<<pt1.get_x()<<", "<<pt1.get_y()<<endl;
cout<<"Pt2 is "<<pt2.get_x()<<", "<<pt2.get_y()<<endl;
cout<<"Pt3 is "<<pt3.get_x()<<", "<<pt3.get_y()<<endl;


pt1 = pt2+pt3;


cout<<"Pt1(=pt2 + pt3) is "<<pt1.get_x()<<", "<<pt1.get_y()<<endl;
Point pt4 = pt1 - pt2;//-操作数
cout<<"pt4(=Pt1 - pt2) " <<pt4.get_x()<<", "<<pt4.get_y()<<endl;
int num = 10;
cout<<"Num is "<<num<<endl;
Point pt5 = num - pt3;//重载-操作数
cout<<"pt5=("<<num<<" - pt3) is:  "<< pt5.get_x()<<", "<<pt5.get_y()<<endl;


pt5 = pt4; //赋值操作符
cout<<"pt5 = pt4 equals "<<pt5.get_x()<<", "<<pt5.get_y()<<endl;
cout<<"pt5 is "<<pt5<<endl;  //这里使用了，<<输出重载符。
return 0;
}