c++多态性相关问题

Question

给出下面的抽象基类container:

要求建立3个继承container的派生类cube、sphere与cylinder，让每一个派生类都包含虚函数surface_area()和volume()，分别用来计算正方体、球体和圆柱体的表面积及体积。要求写出主程序，应用C++的多态性，分别计算边长为6.0的正方体、半径为5.0的球体，以及半径为5.0和高为6.0的圆柱体的表面积和体积。

Answer 1

你找要求写子类就好了啊，哪一步有困难？
参考一下：

#include <iostream>
using namespace std;

#define PI 3.1415926
class container
{
protected:
    double radius;
public:
    container(double radius1);
    virtual double suface_area() = 0;
    virtual double valume() = 0;
};

container::container(double radius1)
{
    radius = radius1;
}

class cube : public container
{
public:
    cube(double radius1) : container(radius1) {}
    double suface_area()
    {
        return 6*radius*radius;
    }
    double valume()
    {
        return radius * radius *radius;
    }
};

class sphere : public container
{
public:
    sphere(double radius1) : container(radius1) {}
    double suface_area()
    {
        return 4*PI*radius*radius;
    }
    double valume()
    {
        return 4.0/3*PI*radius*radius*radius;
    }
};

class cylinder : public container
{
protected:
    double height;
public:
    cylinder(double radius1,double height1) : container(radius1),height(height1) {}
    double suface_area()
    {
        return 2*PI*radius*radius + 2*PI*radius*height;
    }
    double valume()
    {
        return PI*radius*radius * height;
    }
};

int main()
{
    container *p = new cube(6.0);
    cout<<p->suface_area()<<endl;
    cout<<p->valume()<<endl;
    p = new sphere(5.0);
    cout<<p->suface_area()<<endl;
    cout<<p->valume()<<endl;
    p = new cylinder(5.0,6.0);
    cout<<p->suface_area()<<endl;
    cout<<p->valume()<<endl;
    return 0;
}