AWOL:
What do you think sizeof returns?Have another guess.
Some languages won't let you write to memory you don't own.
C is not one of them.
The sizeof was an amature mistake on my part. (I've been spending too much time using R and not enough time using C over the last few months.) I totally get why the loop didn't function properly (which, if I'd bothered to test its output, I would have caught). I still don't understand why it altered the return from Serial.parseInt(). If you (or anyone else) have any insight, I would appreciate it.