#include<iostream>
using namespace std;
const double PI=3.14159;
class Point
{
    protected:
        double x,y;
    public:
        Point(double xv,double yv){ x=xv; y=yv;}
        double Area(){ return 0;}
        void show()
        {
            cout<<"x="<<x<<' '<<"y="<<y<<endl;
        }
};

class Circle:public Point
{
        double radius;
    public:
        Circle(double xv,double yv,double vv):Point(xv,yv)
        {
            radius=vv;
        }
        Circle(Circle &Cir):Point(Cir)
        {
            radius=Cir.radius;
        }
        double Getradius(){    return radius;}
        double Area(){    return PI*radius*radius;}
        void show()
        {
            cout<<"x="<<x<<' '<<"y="<<y<<' '<<"radius="<<radius<<endl;
        }
};

class Cylinder:public Circle
{
    private:
        double h;
    public:
        Cylinder(double xv,double yv,double vv,double xx):Circle(xv,yv,vv)
        {
            h=xx;
        }
        double Area() { return (2*Area()+2*PI*Getradius()*h); }
        Cylinder(Cylinder &p):Circle(p) { h=p.h; }
        void show()
        {
            cout<<"x="<<x<<' '<<"y="<<y<<' '<<"radius="<<Getradius()<<' '<<"h="<<h<<endl;
        }
};

void main()
{
    Point p(1,2);
    cout<<"点的面积="<<p.Area()<<endl;
    p.show();
    Circle c1(1,2,3),c2(c1);
    cout<<"圆的面积="<<c2.Area()<<endl;
    c2.show();
    Cylinder c3(1,2,3,2),c4(c3);
    cout<<"圆柱的面积="<<c4.Area()<<endl;
    c4.show();
}
运行截图：


[ 本帖最后由 子楠 于 2013-4-9 17:28 编辑 ]

x，y是保护的，radius是自己的可以调用啊，那里没有错误，就是派生出的圆柱类那里出问题了

奥，没事。。恩恩，对了，非常感谢