2015年大一下第11周项目4-点、圆的关系（1）重载输入输出函数

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/* *Copyright (c) 2014,烟台大学计算机学院 *All rights reserved. *文件名称:Annpion.cpp *作者:王耀鹏 *完成日期:2015年5月20日 *版本号:v1.0 * *问题描述:以Point为基类，派生出一个Circle(圆)类。*输入描述:无。 *输出描述:输出点与圆之间的位置*/ #include <iostream>#include<cmath>using namespace std;class Circle;class Point{protected:    double x,y;public:    Point(double a,double b):x(a),y(b){}    friend ostream &operator<<(ostream & out,const Point &p);    friend int locate(const Point &p,const Circle &c);};ostream &operator<<(ostream & out,const Point &p){    cout<<"("<<p.x<<","<<p.y<<")"<<endl;    return out;}class Circle:public Point{private:    double r;public:    Circle(double a,double b,double c):Point(a,b),r(c){}    friend ostream &operator<<(ostream & out,const Circle &c);    friend int locate(const Point &p,const Circle &c);};ostream &operator<<(ostream & out,const Circle &c){    cout<<"圆心为："<<"("<<c.x<<","<<c.y<<")"<<"半径为："<<c.r<<endl;    return out;}int locate(const Point &p,const Circle &c){    double distance;    distance=sqrt((p.x-c.x)*(p.x-c.x)+(p.y-c.y)*(p.y-c.y));    if(distance>c.r)        return 1;    else if(distance==c.r)        return 0;    return -1;}int main( ){Circle c1(3,2,4),c2(4,5,5);      //c2应该大于c1Point 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;}

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