C++编程练习：多态实验——利用抽象类和纯虚函数，编程计算正方体、球体和圆柱体的表面积和体积。

//头文件
#include <iostream>
using namespace std;
#define PI 3.141265
class Solid             //定义抽象类
{
protected:
  double r;
  double s, v;
public:
  virtual double S() = 0;
  virtual double V() = 0;
  Solid(double a, double b, double c)
  {
  r = a;
  s = b;
  v = c;
  }
};
class Cube :public Solid
{
public:
  Cube(double a, double b, double c) : Solid(a, b, c)
  {
  }
  double S()
  {
  s = 6 * r * r;
  return s;
  }
  double V()
  {
  v = r * r * r;
  return v;
  }
};
class Sphere :public Solid
{
public:
  Sphere(double a, double b, double c) : Solid(a, b, c)
  {
  }
  double S()
  {
  s = 4 * PI * r * r;
  return s;
  }
  double V()
  {
  v = PI * r * r * r * 4 / 3;
  return v;
  }
};
class Cylinder :public Solid
{
protected:
  double high;
public:
  Cylinder(double h, double r, double a, double v) : Solid(r, a, v)
  {
  high = h;
  }
  double S()
  {
  s = 2 * PI * r * r + 2 * PI * r * high;
  return s;
  }
  double V()
  {
  v = PI * r * r * high;
  return v;
  }
};
double source_area(Solid* p)
{
  return p->S();
}
double volume(Solid* p)
{
  return p->V();
}
//主函数
#include"头文件.h"
#include <iostream>
using namespace std;
int main()
{
  char a;
  double r0, h;
  cout << "请输入正方体的边长：" << endl;
  cin >> r0;
  Cube cube(r0, 0, 0);
  cout << "正方体的表面积为：" << source_area(&cube) << endl << "正方体的体积为：" << volume(&cube) << endl;
  cout << "-------------------------";
  cout << "" << endl;
  cout << "请输入球体的半径：" << endl;
  cin >> r0;
  Sphere sphere(r0, 0, 0);
  cout << "球体的表面积为：" << source_area(&sphere) << endl << "球体的体积为：" << volume(&sphere) << endl;
  cout << "-------------------------";
  cout << "" << endl;
  cout << "请输入圆柱体的的底面半径：" << endl;
  cin >> r0;
  cout << "请输入圆柱体的的高：" << endl;
  cin >> h;
  Cylinder cylinder(r0, h, 0, 0);
  cout << "球体的表面积为：" << source_area(&cylinder) << endl << "球体的体积为：" << volume(&cylinder) << endl;
  system("pause");
  return 0;
}