#include <iostream>

class val_holder
{
public:

  // convert from int to val_holder
  val_holder(int i) : val(i+2) {}

  // convert from val_holder to int
  operator int()
  {
      return val+1;
  }

  void print()
  {
      std::cout << "val_holder = " << val << std::endl;
  }

protected:
  int val;
};

int main(int argc, char** argv)
{
  val_holder v(5);
  v.print(); // prints 7

  // convert from val_holder to int using conversion function
  int i = v;
  std::cout << "i = " << i << std::endl; // prints 8

  // convert from int to val_holder using (non-explicit) conversion constructor
  v = i;

  v.print(); //prints 10

  return 0;
}