// Intro. to Inheritance
// * Probably the most powerful feature of OOP
// * base class --> derived class
// * The derived class inherits all the capablities of the base class
//   but can override received ones and
//           add other features.

#include <iostream.h>
class Circle
{
   private:
      double radius;
   public:
      Circle(double r) { radius = r; }
      double getR() { return radius; }
      double area(void) { return 3.14*radius*radius; }
};

class Cylinder : public Circle
{
   private:
      double len;
   public:
      Cylinder(double l, double r) : Circle(r) { len = l; }
      double getL(void) { return len; }
      double volume(void) { return area()*len; }
};

void main()
{
   Circle c1(1), c2(2);
   cout << "Circle 1: " << "r=" << c1.getR()
                        << " Area=" << c1.area() << endl;
   cout << "Circle 2: " << "r=" << c2.getR()
                        << " Area=" << c2.area() << endl;

   Cylinder cy1(1,1), cy2(2,2);
   cout << "Cylinder 1: " << "r=" << cy1.getR()
                          << ",L=" << cy1.getL()
                          << " Vol=" << cy1.volume() << endl;
   cout << "Cylinder 2: " << "r=" << cy2.getR()
                          << ",L=" << cy2.getL()
                          << " Vol=" << cy2.volume() << endl;
}