// polygon8.cc
#include <iostream>
#include <string>
using namespace std;

class Polygon
{
  public:
    int NumSides;
    virtual void Draw(void) {
      cout << "Drawing polygon with " << NumSides << " sides." << endl;
    }
    Polygon(int sides) {
      NumSides = sides;
    }
};

class Triangle: public Polygon
{
  public:
    Triangle(): Polygon(3) { 
    }
    void Draw(void) { // now this will get used
      cout << "Using special triangle drawing routine" << endl;
    }
};
  
void DrawPolygon(Polygon& poly) {
  poly.Draw();
}

int main()
{
  Polygon MyPentagon(5);
  Triangle MyTriangle;
  DrawPolygon(MyPentagon);
  // Now thanks to virtual functions, the correct (more specialized)
  // version of the Draw() routine will be used, i.e., Triangle::Draw()
  DrawPolygon(MyTriangle); 
}