第十一周任务四多重继承

#include <iostream>
using namespace std;
class Point
{
    public:
    Point(double x1=0,double y1=0){x=x1;y=y1;}
    double returnx(){return x;}
    double returny(){return y;}
    private :
    double x;
    double y;

};
class Circle:public Point
{
    public:Circle(double x,double y,double r1):Point(x,y)
    {
        r=r1;
    }
    double area()
    {
        double area;
        area=3.14*r*r;
        return area;
    }
    double l()
    {
        return 3.14*2*r;
    }
    double returnr(){return r;}
    private:
    double r;

};
class Cylinder:public Circle
{
    public:
    Cylinder(double x,double y,double r,double h1):Circle(x,y,r)
    {
        h=h1;
    }
    double v(){return area()*h;}
    double s(){return l()*h+2*area();}
    double returnh(){return h;}
    friend ostream &operator<<(ostream &output, Cylinder& cy)
{
    output<<"Center=["<<cy.returnx()<<","<<cy.returny()<<"], r="<<cy.returnr()<<", h="<<cy.returnh()
    <<"\narea="<<cy.s( )<<", volume="<<cy.v( )<<endl;
    return output;
}
    private :
    double h;
};

int main()
{
    Cylinder x(7.9,9.8,4.6,3.5);
    cout<<x;
    return 0;
}