#include <iostream>

/* this is an abstract class in C++ */
class Honkable {
  public:
    void honk(int n) {
      for (int i = 0; i < n; i++) {
        std::cout << "honk!";
      }
      std::cout << std::endl;
    }
};

/* a concrete implementation */
class Car : public Honkable {
  public:
    void honk(int n) {
      for (int i = 0; i < n; i++) {
        std::cout << "beep!";
      }
      std::cout << std::endl;
    }
};

void honk(Honkable *h, int n) {
  // honk it!
  h->honk(n);
}

int main() {
  Car *h1 = new Car();
  // this does not do what we want!
  honk(h1, 5);
  // we have to "pay" for this feature!
}