poly-pure.cpp

适合初学者学习以及程序员回顾

// Poly-Pure.cpp

#include <iostream>
using std::cin;
using std::cout;
using std::endl;

//---- 宣告类别 Shape --------
class Shape
{
private:
  int i;
public:
  Shape(): i(7){}
  ~Shape(){}
  virtual void Draw() =0;
  virtual void Erase()=0;
};

//---- 宣告类别 Circle--------
class Circle : public Shape
{
private:
  int r;
public:
  Circle(): r(5)      {}
  Circle(int N): r(N) {}
  ~Circle()           {}
  void Draw()  {cout<<"画一个圆形\n";}
  void Erase() {cout<<"把圆形清除\n";}
};

//---- 宣告类别 Cylinder--------
class Cylinder : public Circle
{
private:
  int r, h;
public:
  Cylinder(): r(5), h(1)    {}
  Cylinder(int M, int N): r(M), h(N) {}
  ~Cylinder()         {}
  void Draw()  {cout<<"画一个圆柱形\n";}
  void Erase() {cout<<"把圆柱形清除\n";}
};

void Make(Shape &S1) {S1.Draw();}
void Remove(Shape *pS) {pS->Erase();}

// ----主程式---------------------------
main()
{
  Circle   C1;
  Cylinder CyL;
  Shape    *pS;
  cout << "“Make(C1))” : ";
  Make(C1);
  cout << "“Make(CyL))”: ";
  Make(CyL);
  cout << "执行 “pS=&C1”   之后: " << endl;
  pS=&C1;
  cout << "“Remove(pS)”: ";
  Remove(pS);
  cout << "执行 “pS=&CyL”  之后: " << endl;
  pS=&CyL;
  cout << "“Remove(pS)”: ";
  Remove(pS);
}