11.4.3

#include <iostream>using namespace std;class Point{public:Point(double x=0,double y=0); //构造函数void setPoint(double,double);                  //设置坐标值double getX( ) const {return x;}              //读x坐标double getY( ) const {return y;}              //读y坐标friend ostream & operator<<(ostream &,const Point &);//重载运算符“<<”protected: //受保护成员double x,y;};//Point的构造函数Point::Point(double a,double b){x=a;y=b;}//设置x和y的坐标值void Point::setPoint(double a,double b)  {x=a;y=b;}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 x=0,double y=0,double r=0);  //构造函数void setRadius(double);                  //设置半径值double getRadius( ) const;               //读取半径值double area ( ) const;                   //计算圆面积friend ostream &operator<<(ostream &,const Circle &);//重载运算符“<<”protected:double radius;};//定义构造函数，对圆心坐标和半径初始化Circle::Circle(double a,double b,double r):Point(a,b),radius(r){ }//设置半径值void Circle::setRadius(double r){radius=r;}//读取半径值double Circle::getRadius( ) const{return radius;}//计算圆面积double Circle::area( ) const{return 3.14159*radius*radius;}//重载运算符“<<”，使之按规定的形式输出圆的信息ostream &operator<<(ostream &output,const Circle &c){output<<"Center=["<<c.x<<", "<<c.y<<"], r="<<c.radius<<", area="<<c.area( )<<endl;return output;}class Cylinder:public Circle{public:Cylinder (double x=0,double y=0,double r=0,double h=0);//构造函数void setHeight(double);                      //设置圆柱高double getHeight( ) const;                    //读取圆柱高double area( ) const;                         //计算圆柱表面积double volume( ) const;                       //计算圆柱体积friend ostream& operator<<(ostream&,const Cylinder&);//重载运算符“<<”protected:double height;                               //圆柱高};//定义构造函数Cylinder::Cylinder(double a,double b,double r,double h) :Circle(a,b,r),height(h){}//设置圆柱高void Cylinder::setHeight(double h){height=h;}//读取圆柱高double Cylinder::getHeight( ) const {return height;}//计算圆柱表面积double Cylinder::area( ) const{ return 2*Circle::area( )+2*3.14159*radius*height;}//计算圆柱体积double Cylinder::volume() const{return Circle::area()*height;}//重载运算符“<<”ostream &operator<<(ostream &output,const Cylinder& cy){output<<"Center=["<<cy.x<<","<<cy.y<<"], r="<<cy.radius<<", h="<<cy.height<<"\narea="<<cy.area( )<<", volume="<<cy.volume( )<<endl;return output;}int main( ){Cylinder cy1(3.5,6.4,5.2,10);cout<<"\noriginal cylinder:\nx="<<cy1.getX( )<<", y="<<cy1.getY( )<<", r="<<cy1.getRadius( )<<", h="<<cy1.getHeight( )<<"\narea="<<cy1.area()<<",volume="<<cy1.volume()<<endl;cy1.setHeight(15);     cy1.setRadius(7.5);      cy1.setPoint(5,5);       cout<<"\nnew cylinder:\n"<<cy1;        return 0;}