11.7.cpp

这是C++的一部分练习程序!对初学者有一定的帮助作用。

#include <iostream.h>
const double PI=3.14159265;
class Point
{
  public:
	Point(double i,double j)
	{  x=i;y=j;  }
	double Area()
	{  return 0;  }
  private:
	double x,y;
};
class Rectangle:public Point
{
  public:
	Rectangle(double i,double j,double k,double l):Point(i,j)
	{  w=k;h=l;  }
	double Area()
	{  return w*h;  }
  private:
	double w,h;
};
class Circle:public Point
{
  public:
	Circle(double i,double j,double k):Point(i,j)
	{  r=k;  }
	double Area()
	{  return PI*r*r;  }
  private:
	double r;
};
void fun(Point &p)
{
	cout<<"Area= "<<p.Area()<<endl;
}
void main()
{
	Rectangle r(3.5,4,5.2,6.6);
	Circle c(4.5,6.2,5);
	fun(r);
	fun(c);
}