1 #include <iostream>
  2 using namespace std;
  3 class point 
  4 {
  5     int x;
  6     int y;
  7 public :
  8     point ()
  9     {
 10         x=y=0;
 11     }
 12     point (int a,int b)
 13     {
 14         x=a;
 15         y=b;
 16     }
 17     ~point (){}
 18     void show ()
 19     {
 20         cout <<"("<<x<<","<<y<<")"<<endl;
 21     }
 22 };
 23 class Shape
 24 {
 25 private:
 26     double longth;
 27     double width;
 28 public :
 29     Shape ()
 30     {
 31         longth=width=0;
 32     }
 33     Shape (double l,double w)
 34     {
 35         longth=l;
 36         width=w;
 37         cout<<"构造函数，创建Shape"<<endl;
 38     }
 39     ~Shape()
 40     {
 41         cout <<"析构函数，释放Shape"<<endl;
 42     }
 43     double area()
 44     {
 45         double s;
 46         s=longth*width;
 47         return s;
 48     }
 49     void show ()
 50     {
 51         cout <<"面积="<<area()<<endl;
 52     }
 53 };
 54 class Rectangle:public Shape
 55 {
 56 public :
 57     Rectangle():Shape(0,0){}
 58     Rectangle(double a,double b):Shape(a,b)
 59     {
 60         cout<<"创建Rectangle"<<endl;
 61     }
 62     void show ()
 63     {
 64         cout <<"面积="<<area()<<endl;
 65     }
 66     ~Rectangle()
 67     {
 68         cout <<"析构函数，释放Rectangle"<<endl;
 69     }
 70 };
 71 class Square:public Rectangle
 72 {
 73 public :
 74     Square(double a):Rectangle(a,a)
 75     {
 76         cout<<"构造函数，创建Square"<<endl;
 77     }
 78     ~Square()
 79     {
 80         cout <<"析构函数，释放Square"<<endl;
 81     }
 82 };
 83 class Circle:public Shape
 84 {
 85 private :
 86     double r;
 87     point p;
 88 public :
 89     Circle(double c,point n):Shape(c,c)
 90     {
 91         r=c;
 92         p=n;
 93         cout<<"构造函数，创建Circle"<<endl;
 94     }
 95     ~Circle()
 96     {
 97         cout <<"析构函数，释放Circle"<<endl;
 98     }
 99     double area()
100     {
101         double s;
102         s=3.14*r*r;
103         return s;
104     }
105     void show ()
106     {
107         cout <<"面积="<<area()<<endl;
108     }
109 };
110 int main()
111 {
112     Rectangle r(2,4);
113     r.show();
114     point o(1,1);
115     Circle c (4.0,o);
116     c.show ();
117     Square s(4);
118     s.show();
119     return 0;
120 }