继承性

#include<iostream>
using namespace std;

class point
{ private:  int x,y;
  public:    void set_xy(int sx,int sy)  {  x=sx;y=sy;}
         int get_x()                     {  return x; }
		 int get_y()                     {  return y; }
};

class circle:public point
{  private:  float r;
public: 
void set_r(float sr)    {r=sr; }
void disp()  
{   cout<< get_x()<<"   "<<get_y()<<endl;
    cout<<r<<endl;
}
};

 int main()
{
 circle c;
   c.set_xy(5,10);
   c.set_r(10.5f);
   c.disp();
}