Re: enum and operator++

Dear all
I am struggling with a problem that's simple per se.
I have an enum and a prefix ++ operator:
enum Dir { North = 1, East = 2, South = 3, West = 4, Max_ = 5 }=

clockwise

Dir operator++(Dir d)
{
  Dir dd;
  switch (d) {
  case North:
    dd = East;
    break;
  case East:
    dd = South;
    break;
  case South:
    dd = West;
    break;
  case West: // wrap
    dd = North;
    break;
  };

  return dd;

}

void f()
{
   for (Dir d = North; d < Max_; ++d)
    // do something

}

The problem is: in the above loop the ++ doesn't work,
indeed the loop is infinite. If you replace // do something with
output statement, it prints 1 forever.