Quote Originally Posted by freddyvorhees View Post
Where should I do the modification in main or in the function?
All you should change is the function -- which means you shouldn't change the function prototype (must still accept and return unsigned long), so that main still knows what's going on. It seems they want you to print (i) the parameter passed in and (ii) the parameter that is called in the recursive call (where applicable) -- or at least that's how I read the assignment.