第7周项目1（2） 成员函数，友元函数和一般函数的区别 两点距离类

/* <p><span><span class="comment">02. *Copyright (c) 2016，烟台大学计算机学院</span> </span></p><p class="alt"><span><span class="comment">03. *All rights reserved.</span> </span></p><p><span><span class="comment"> 04. *文件名称：cpp</span> </span></p><p class="alt"><span><span class="comment"> 05. *作    者：孙亚茹</span> </span></p><p><span><span class="comment">06. *完成日期：2016年4月14日</span> </span></p><p class="alt"><span><span class="comment">07. *版 本 号：v1.0</span> </span></p><p><span><span class="comment"> 09. *问题描述：写出三种形式的函数</span> </span></p><p class="alt"><span><span class="comment">*/</span><span>  </span></span></p>

#include <iostream>#include<cmath>using namespace std;class Cpoint{public:    Cpoint(double xx=0,double yy=0):x(xx),y(yy){}    friend void distance2(Cpoint &x,Cpoint &y);    void distance3(Cpoint &x,Cpoint &y);    double getX(){return x;}    double getY(){return y;}private:    double x;    double y;};void distance2(Cpoint &p1,Cpoint&p2){    double d,d1;    d=(p1.x-p2.x)*(p1.x-p2.x)+(p1.y-p2.y)*(p1.y-p2.y);    d1=sqrt(d);    cout<<"两点之间距离为: "<<d1<<endl;} void distance3(Cpoint &p1,Cpoint &p2){    double d,d1;    d=(p1.getX()-p2.getX())*(p1.getX()-p2.getX())+(p1.getY()-p2.getY())*(p1.getY()-p2.getY());    d1=sqrt(d);    cout<<"两点之间距离为: "<<d1<<endl;}int main(){   Cpoint p1(10,5);   Cpoint p2(1,6);   distance2(p1,p2);   distance3(p1,p2);    return 0;}