第13周 点圆关系

/**Copyright (c)2013,烟台大学计算机学院*All rights reserved.*文件名称：test.cpp*作者：赵振凯*完成日期：2014年5月21日*版本号：v1.0*输入描述：无*问题描述：点圆的关系*/#include <iostream>#include<Cmath>using namespace std;class Point{public:    Point(double a=0,double b=0):x(a),y(b) {} //构造函数    double distance(const Point &p) const;//求距离    friend ostream & operator<<(ostream &,const Point &);//重载运算符“<<”protected:  //受保护成员    double x,y;}; double Point::distance(const Point &p) const//求距离{    double dx = x-p.x;    double dy = y-p.y;    return sqrt(dx*dx+dy*dy);} ostream & operator<<(ostream &output,const Point &p){    output<<"["<<p.x<<","<<p.y<<"]"<<endl;    return output;} class Circle:public Point //circle是Point类的公用派生类{public:    Circle(double a=0,double b=0,double r=0) :Point(a,b),radius(r) { }; //构造函数    friend ostream &operator<<(ostream &,const Circle &);//重载运算符“<<”    friend int locate(const Point &p, const Circle &c); //判断点p在圆上、圆内或圆外，返回值：<0圆内，==0圆上，>0 圆外protected:    double radius;}; ostream &operator<<(ostream &output,const Circle &c){    output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<endl;    return output;} //判断点p在圆内、圆c内或圆c外int locate(const Point &p, const Circle &c){    const Point cp(c.x,c.y); //圆心    double d = cp.distance(p);    if (abs(d - c.radius) < 1e-7)        return 0;  //相等    else if (d < c.radius)        return -1;  //圆内    else        return 1;  //圆外} int main( ){    Circle c1(3,2,4);    Point p1(1,1),p2(3,-2),p3(7,3);  //分别位于c1内、上、外     cout<<"圆c1: "<<c1;     cout<<"点p1: "<<p1;    cout<<"点p1在圆c1之"<<((locate(p1, c1)>0)?"外":((locate(p1, c1)<0)?"内":"上"))<<endl;     cout<<"点p2: "<<p2;    cout<<"点p2在圆c1之"<<((locate(p2, c1)>0)?"外":((locate(p2, c1)<0)?"内":"上"))<<endl;     cout<<"点p3: "<<p3;    cout<<"点p3在圆c1之"<<((locate(p3, c1)>0)?"外":((locate(p3, c1)<0)?"内":"上"))<<endl;    return 0;}