DK型控制器由哪几部分组成？各部分的作用是什么？

[说明]
下面程序计算正方体、球体和圆柱体的表面积和体积。
[C++程序]
#include＜iostream.h＞
class container

protected:
double radius;
public：
container(double radius)

container::radius=radius;

(1) ;
(2) ;
;
class cube: (3)

public：
cube(double radius)::container(radius)();
double surface_area()

return radius*radius*6;

double volume()

return radius*radius*radius;

;
class sphere: public container

(4) ;
double surface_area()

return 4*3.1416 *radius*radius;

double volume()

return 3.1416*radius *radius*radius*4/3;

;
class cylinder:public container

double height;
public：
cylinder(double radius, double height):container(radius)

(5) ;

double surface_area()

return 2*3.1416*radius*(height+radius);

double volume()

return 3.1416 *radius*radius*height;

;
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()＜＜endl;
cout＜＜"正方体体积："＜＜p-＞volume()＜＜endl;
p=＆obj2;
cout＜＜"球体表面积："＜＜p-＞surface_area()＜＜endl;
cout＜＜"球体体积："＜＜p-＞volume()＜＜endl;
p=＆obj3;
cout＜＜"圆柱体表面积："＜＜p-＞surface_area()＜＜endl;
cout＜＜"圆柱体体积："＜＜p-＞volume()＜＜endl;