c++知识点----定义抽象基类（纯虚函数）

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题目：

写一个函数，定义抽象基类Container，由它派生出3个派生类：Sphere（球体）、Cylinder（圆柱体）、Cube（正方体）。用虚函数分别计算几种图形的表面积和体积

用到的文件

main.cpp

#include <iostream>
using namespace std;
#define PI 3.14159
#include "class.h"
int main()
{Sphere s1(3);cout << "面积：" << s1.area() << endl;cout << "体积：" << s1.volume() << endl;Cylinder c1(3,3);cout << "面积：" << c1.area()<< endl;cout << "体积：" << c1.volume() << endl;Cube cu1(3);cout << "面积：" << cu1.area() << endl;cout << "体积：" << cu1.volume() << endl;system("pause");return 0;
}

class.h

#pragma once
class Container
{
public:Container(double r,double h);//初始化私有变量Container(double );virtual double area() = 0;//虚函数 -- 计算面积virtual double volume() = 0;//虚函数 -- 计算体积
protected:double R;double highth;};
Container::Container(double r, double h):R(r),highth(h)
{	}
inline Container::Container(double r):R(r),highth(r)
{	}//------------------------------------------------
class Sphere: public Container //球体
{
public:Sphere(double r);virtual double area();//返回球体的面积virtual double volume();//返回球体的体积
private:};
Sphere::Sphere(double r):Container(r)
{	}
inline double Sphere::area()
{return 4*PI*R;
}
inline double Sphere::volume()
{return (4.0/3)*PI*R*R*R;
}
//-------------------------------------------------
class Cylinder:public Container   //圆柱体
{
public:Cylinder(double r,double h);//初始化virtual double area();//计算圆柱体的面积virtual double volume();//计算圆柱体的体积
private:};Cylinder::Cylinder(double r,double h):Container(r,h)
{	}
inline double Cylinder::area()
{return 2*PI*R*R + 2*PI*R*highth;
}
inline double Cylinder::volume()
{return PI*R*R*highth;
}
//-------------------------------------------------
class Cube:public Container //正方体
{
public:Cube(double h);virtual double area();//计算正方体的面积virtual double volume();//计算正方体的体积
private:};
Cube::Cube(double h):Container(h)
{	}
inline double Cube::area()
{return 6*highth*highth;
}
inline double Cube::volume()
{return highth*highth*highth;
}

运行结果：

分别是球体、圆柱体、正方体