#include <iostream>
#include <stdlib.h>

class A {
 public:
 void func () {
  std::cout << "func_a\n";
 }
};

class B {
 public:
 void func () {
  std::cout << "func_b\n";
 }
};

int main () { 
 A a;
 B &b = (B &) a;

 a.func();
 b.func();

 ((B &)a).func();

 return EXIT_SUCCESS;
}