#include <iostream>#include <cmath>using namespace std;class Point{public:    Point(double a,double b):x(a),y(b) {}    double getx()    {        return x;    }    double gety()    {        return y;    }    friend ostream&operator << (ostream&,Point&);protected:    double x,y;};ostream&operator << (ostream &output,Point &p){    output<<"("<<p.getx()<<","<<p.gety()<<")"<<endl;    return output;}class Circle:public Point{public:    Circle(double a,double b,double c):Point(a,b),r(c) {}    double getr()    {        return r;    }    friend ostream&operator << (ostream&,Circle&);    friend double locate(Circle&,Point&);protected:    double r;};ostream&operator << (ostream &output,Circle &c){    output<<"("<<c.getx()<<","<<c.gety()<<")"<<" ";    output<<"r="<<c.getr()<<endl;    return output;}double locate(Point &po,Circle &ci){    double d,num;    d=sqrt(pow((ci.getx()-po.getx()),2)+pow((ci.gety()-po.gety()),2));    if(d>ci.getr())        num=1;    else if(d==ci.getr())        num=0;    else        num=-1;    return num;}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;    return 0;}

感悟：还没吃饭呢！