C++ Randomly change var to enum that is not itself

At the moment, I can randomly choose from an enum and assign it to my variable:

(*itL).setDirection(static_cast<LadyDirection>(rand()% NUM_DIRECTIONS));

void Ladybug::setDirection(LadyDirection temp_direction)
{
    this->direction = temp_direction;
}

enum LadyDirection
{
    North,
    East,
    South,
    West,
    NUM_DIRECTIONS
};

What I want to do is make this change to a random enum value, that isn't what it currently is. Eg. If the direction is == North, set it to East, West or South, randomly.

I know I could do this with a few if/elseif statements, but I'd rather know if there's someway to do this nicer.

Thanks.