// abstract4.cpp
// with polymorphism and PURE virtual functions, still works
#include <iostream>
using namespace std;

class B {
public:
  virtual int get_val() = 0;
};

class D1 : public B {
public:
  D1(int x_val): x(x_val) {};
  virtual int get_val() {return x;};
private:
  int x;
};

class D2 : public B {
public:
  D2(int y_val): y(y_val) {};
  virtual int get_val() {return y*y;};
private:
  int y;
};
 
main()
{ const int MAX =5;
  D1 Zero(0), One(1), Two(2);
  D2 Three(3), Four(4);
  
  B * B_Array[MAX];
  B_Array[0] = &Zero; B_Array[1] = &One;
  B_Array[2] = &Two;  B_Array[3] = &Three; B_Array[4] = &Four;
  
  for (int i = 0; i < MAX; ++i) {
    cout << i <<": " << B_Array[i]->get_val() << endl;
  }
}