//  A2_1.cpp

#include <iostream>
using namespace std;

class B { 
  
  int x;  // data members needed to show the
          // indexing error, e.g., class objects
          // need to be different sizes
public:
  virtual ~B() {}
  virtual void mf() { cout << "\n  B::mf()"; }
};

class D : public B {

  int y;

public:
  virtual void mf() { cout << "\n  D::mf()"; }
};

void fun(B *pB) {

  pB[0].mf();
//  pB[1].mf();   This statement will cause access violation
//                if input is an array of derived objects
//                even though the compiler accepts them with
//                no warning.
}

void main() {

  D da[2];
  fun(da);
  cout << "\n\n";
}