第十一周上机实践项目4——类族的设计（3）

（3）再以Circle类为直接基类，派生出一个Cylinder(圆柱体)类，再增加数据成员h(高)，，以及求圆柱表面积的成员函数area和求圆柱体积的成员函数volume，实现需要的成员函数，并设计main函数完成测试。

代码

#include<iostream>
#include<Cmath>
using namespace std;
class Point
{
protected:
    double x,y;
public:
    Point(double xx,double yy):x(xx),y(yy){}
    double getx()
    {
        return x;
    }
    double gety()
    {
        return y;
    }
    void show1();
};
void Point::show1()
{
    cout<<"底面圆心坐标:"<<"("<<x<<","<<y<<")"<<endl;
}
class Circle:public Point
{
protected:
    double r,area;
public:
    Circle(double xx,double yy,double rr):Point(xx,yy),r(rr){}
    double getarea();
    void show2();
    double getr()
    {
        return r;
    }
};
double Circle::getarea()
{
    area=r*r*3.14;
    return area;
}
void Circle::show2()
{
    show1();
    cout<<"底面积:"<<getarea()<<endl;
}
class Cylinder:public Circle
{
protected:
    double h,volume;
public:
    Cylinder(double xx,double yy,double rr,double hh):Circle(xx,yy,rr),h(hh){}
    double getvolume();
    friend ostream &operator<<(ostream &out,Cylinder &c);
    double geth()
    {
        return h;
    }
};
double Cylinder::getvolume()
{
    volume=getarea()*h;
    return volume;
}
ostream &operator<<(ostream &out,Cylinder &c)
{
    c.show2();
    out<<"体积:"<<c.getvolume()<<endl;
    return out;
}
int main()
{
    Cylinder c(2.2,3.3,4.4,5.5);
    cout<<"该圆柱体的属性:"<<endl;
    cout<<"底面半径:"<<c.getr()<<endl;
    cout<<"高:"<<c.geth()<<endl;
    cout<<c;
    return 0;
}

运行结果：