第十二周项目四 点、圆的关系-（2）重载关系运算符比较两个圆的面积

项目要求

在圆类上重载关系运算符（6种），使之能够按圆的面积比较两个圆的大小。自编main函数完成测试。

代码如下

#include <iostream>#include <cmath>using namespace std;class Point    {public:    Point(double a,double b)        {        x=a;        y=b;        }    double get_distance(Point &p);    friend ostream & operator<<(ostream &out,const Point &p);protected:    double x;    double y;    };double Point::get_distance(Point &p)    {    return sqrt((p.x-x)*(p.x-x)+(p.y-y)*(p.y-y));    }ostream & operator<<(ostream &out,const Point &p)    {    out<<"("<<p.x<<","<<p.y<<")"<<endl;    return out;    }class Circle:public Point    {public:    Circle(double a,double b,double r):Point(a,b),r(r) {}    friend int locate(Point p,Circle c);    friend ostream & operator<<(ostream &out,const Circle &c);    bool operator>(Circle &c);    bool operator<(Circle &c);    bool operator==(Circle &c);    bool operator>=(Circle &c);    bool operator<=(Circle &c);    bool operator!=(Circle &c);protected:    double r;    double area=3.141*r*r;    };int locate(Point p,Circle c)    {    Point cc(c.x,c.y);    double d=p.get_distance(cc);    if (d>c.r)        return 1;    else if (d<c.r)        return -1;    else        return 0;    }ostream & operator<<(ostream &out,const Circle &c)    {    out<<"圆心为：("<<c.x<<","<<c.y<<")，半径为："<<c.r<<endl;    return out;    }bool Circle::operator>(Circle &c)    {    if (area>c.area)        return true;    return false;    }bool Circle::operator<(Circle &c)    {    if (area<c.area)        return true;    return false;    }bool Circle::operator==(Circle &c)    {    if (area==c.area)        return true;    return false;    }bool Circle::operator>=(Circle &c)    {    if (area>=c.area)        return true;    return false;    }bool Circle::operator<=(Circle &c)    {    if (area<=c.area)        return true;    return false;    }bool Circle::operator!=(Circle &c)    {    if (area!=c.area)        return true;    return false;    }int main( )    {    Circle c1(3,2,4),c2(4,5,5);      //c2应该大于c1    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;    cout<<endl<<"圆c1 （";    if(c1>c2) cout<<"大于, ";    if(c1<c2) cout<<"小于, ";    if(c1>=c2) cout<<"大于等于, ";    if(c1<=c2) cout<<"小于等于, ";    if(c1==c2) cout<<"等于, ";    if(c1!=c2) cout<<"不等于, ";    cout<<"） 圆c2"<<endl;    return 0;    }

运行结果