C++由圆派生球，圆柱，圆锥

思路

设计的一个基类Circle类，再分别派生出圆球类Ball，圆锥类Taper 圆柱类Cylinder使用相关编程题方法求出圆的面积，其他几何图形的表面积和体积

#include <cmath>
using namespace std;
const long double PI = 3.1415926;
class Circle
{
    public:
        virtual long double area() = 0;//获得表面积
        virtual long double volume() = 0;//获得体积
};
//球
class Ball:public Circle
{
    public:
        Ball(long double radius):m_radius(radius){}
        long double volume(){
            return 4.0/3.0 * PI * m_radius * m_radius * m_radius;
        }
        long double area(){
            return 4 * PI * m_radius * m_radius;
        }
    private:
        long double m_radius;        //球的半径
};
//圆柱
class Cylinder:public Circle{
    public:
        Cylinder(long double radius, long double high):m_radius(radius),m_high(high){}
        long double volume(){
            return PI * m_radius * m_radius * m_high;
        }
        long double area(){
            return PI * m_radius * m_radius + 2.0 * PI * m_radius * m_high;
        }
    private:
        long double m_radius;   //圆柱的半径
        long double m_high;     //圆柱的高
};
//圆锥
class Taper :public Circle
{
    public:
        Taper (long double radius, long double high):m_radius(radius),m_high(high){
            this->m_coneElement = sqrt(m_high * m_high + m_radius * m_radius);
        }
        long double volume(){
            return 1.0/3.0 * PI * m_radius * m_radius * m_high;
        }
        long double area(){
            return PI * m_radius * (m_radius + m_coneElement);
        }
    private:
        long double m_radius;//圆锥的半径
        long double m_high;  //圆锥的高
        long double m_coneElement;  //圆锥的母线长

};

int main()
{
    Circle *p = NULL;
    p = new Taper (3,4);
    cout << "圆锥(3,4)的表面积是：" << p->area() << " 体积是：" << p->volume() << endl;
    delete p;
    p = NULL;
    //
    p = new Cylinder(6,4);
    cout << "圆柱(6,4)的表面积是：" << p->area() << " 体积是：" << p->volume() << endl;
    delete p;
    p = NULL;
    //
    p = new Ball(6);
    cout << "球(6)的表面积是：" << p->area() << " 体积是：" << p->volume() << endl;
    delete p;
    p = NULL;
    //
    return 0;
}