【说明】
以下程序的功能是计算正方体、球体和圆柱体的表面积和体积并输出。
程序由4个类组成：类cube、sphere和cylinder分别表示正方体、球体和圆柱体；抽象类 container为抽象类，提供了两个纯虚拟函数surface_area()和volum()，作为通用接口。
【C++程序】
#include＜iostream.h＞
#define pi 3.1416
class container｛
protected:
double radius;
public:
container(double radius) container::radius=radius;
virtual double surface_area()=0;
virtual double velum()=0;
;
class cube: (1) //定义正方体类
public:
cube(double radius):container(radius);
double surface_area () return 6 * radius * radius;
double volum() return radius * radius * radius;
;
class sphere: (2) //定义球体类
public:
sphere(double radius): container(radius);
double surface_area() return (3) ;
double volum() return pi * radius * radius * radius * 4/3;
;
class cylinder: (4) //定义圆柱体类
double height;
public:
cylinder(double radius,double height):container(radius)
container::height=height;
double surface_are a () return 2 * pi * radius * (height+radius);
double volum () return (5) ;
;
void main()
container * p;
cube obj1 (5);
sphere obj2(5);
cylinder obj3(5,5);
p=&obj1;
cout＜＜“正方体表面积”(＜＜p-＞surface_area()＜＜end1;
cont＜＜“正方体体积”＜＜p-＞volume()＜＜end1;
p=&obj2;
cout＜＜“球体表面积”＜＜p-＞surface_area()＜＜end1;
cout＜＜“球体体积”＜＜p-＞volume()＜＜end1;
p=&obj3;
cout＜＜“球体表面积”＜＜p-＞surface_area()＜＜end1;
cout＜＜“球体体积”＜＜p-＞volume()＜＜end1;