“int main (vooid)”? How does that work?

Question

I recently had to type in a small C test program and, in the process, I made a spelling mistake in the main function by accidentally using vooid instead of

Answer 1

It's valid code, because myprog.c contains:

int main (vooid) // vooid is of type int, allowed, and an alias for argc
{     
  return 42; // The answer to the Ultimate Question
} 

vooid contains one plus the number of arguments passed (i.e., argc). So, in effect all you've done is to rename argc to vooid.