我觉得值得注意的是他用了输入输出的运算符重载：
#include<iostream>
using namespace std;
class Point
{
protected:
double x,y;
public:
Point(double x=0,double y=0);
void setPoint(double x,double y);
double getx(){return x;}
double gety(){return y;}
friend ostream & operator<<(ostream &,const Point &);
};
class Cricle:public Point
{
protected:
double radius;
public:
Cricle(double r=0,double x=0,double y=0);
void setCricle(double r);
double getr(){return radius;}
double getarea(){return 3.14*radius*radius;}
friend ostream & operator<<(ostream &,const Cricle &);
};
class Crylinder:public Cricle
{
protected:
double height;
public:
Crylinder(double h=0,double r=0,double x=0,double y=0);
void setCrylinder(double h);
double geth(){return height;};
double getarea(){return 2*Cricle::getarea()+2*3.14*radius*height;}
double getvolume(){return height*Cricle::getarea();}
friend ostream &operator<<(ostream &,const Crylinder &);
};
Point::Point(double x,double y)
{setPoint(x,y);}
void Point::setPoint(double x,double y)
{this->x=x;this->y=y;}
Cricle::Cricle(double r,double x,double y):Point(x,y){radius=r;}
void Cricle::setCricle(double r){radius=r;}
Crylinder::Crylinder(double h,double r,double x,double y):Cricle(r,x,y){height=h;}
void Crylinder::setCrylinder(double h){height=h;}
ostream &operator<<(ostream & output,const Point& p)
{
output<<"Point\n"<<"("<<p.x<<","<<p.y<<")"<<endl;
return output;
}
ostream &operator<<(ostream & output,const Cricle &c)
{
output<<"Cricle\n"<<"the radius is:"<<c.radius<<"\nthe center is the point:"<<"("<<c.x<<","<<c.y<<");\n";
return output;
}
ostream & operator<<(ostream & output,const Crylinder &cr)
{
output<<"Crylinder\n"<<"height:"<<cr.height<<"\tradius:"<<cr.radius<<"\t center point:"<<"("<<cr.x<<","<<cr.y<<");\n";
return output;}
int main()
{
Point p1(1,2);
p1.setPoint(2,3);
cout<<p1;
Cricle c1(3,4,5);
c1.setCricle(4);
cout<<c1;
cout<<"area: "<<c1.getarea()<<endl;
Crylinder cr(7,8,9,10);
cr.setCrylinder(10);
cout<<cr;
cout<<"area: "<<cr.getarea()<<"\t"<<"volume: "<<cr.getvolume()<<endl;
return 0;
}