（一）计算两点之间的距离（友元函数）

#include<iostream>

#include<cmath>

#define OK 1

using namespace std;

class Point

{

public:

Point(int xx=0,int yy=0) { X=xx; Y=yy; }

int GetX() { return X; }

int GetY() { return Y; }

friend float fDist(Point &a,Point &b); //友元函数声明

private:

int X,Y;

};

float fDist(Point &p1,Point &p2)//友元函数实现

{

double x=double(p1.X-p2.X); //通过对象访问私有数据成员

double y=double(p1.Y-p2.Y);

return float(sqrt(x*x+y*y));

}

int main()

{

int x1,y1,x2,y2;

Point myp1(1,1),myp2(4,5);//定义Point类的对象

cout<<"The distance is : "<<fDist(myp1,myp2)<<endl<<endl;//计算两点间的距离

cout<<"请输入第一个点的坐标（x1,y1）： ";

cin>>x1>>y1;

cout<<"请输入第二个点的坐标（x2,y2）： ";

cin>>x2>>y2;

Point youp1(x1,y1),youp2(x2,y2);

cout<<"The distance is : "<<fDist(youp1,youp2)<<endl;//计算两点间的距离

return OK;

}

转自：silence http://blog.csdn.net/jqh2002_blog/article/details/24842761