第6周项目4

#include <iostream>#include <cmath>using namespace std;class CPoint{private:    double x;  // 横坐标    double y;  // 纵坐标public:    CPoint(double xx=0,double yy=0):x(xx),y(yy){}    double distance1(const CPoint p);    friend double distance2(CPoint &,CPoint &);    double getx();    double gety();};double CPoint::distance1(CPoint p){    double d;    d=sqrt((p.x-x)*(p.x-x)+(p.y-y)*(p.y-y));    return d;}double distance2(CPoint &p1,CPoint &p){   double d;   d=sqrt((p.x-p1.x)*(p.x-p1.x)+(p.y-p1.y)*(p.y-p1.y));   return d;}double CPoint::getx(){    return x;}double CPoint::gety(){    return y;}double distance3(CPoint &p3,CPoint &p4){    double d;    d=sqrt((p3.getx()-p4.getx())*(p3.getx()-p4.getx())+(p3.gety()-p4.gety())*(p3.gety()-p4.gety()));    return d;}int main(){    CPoint p1(1,1),p2(2,2);    cout<<"距离为"<<p1.distance1(p2)<<endl;    cout<<distance2(p1,p2)<<endl;    cout<<distance3(p1,p2)<<endl;    return 0;}

 

 

 

友元函数两个点的对象需要去引用。