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.
What do you think was in the extra memory you were clobbering? Maybe some of it was part of the serial buffer ... or some of the many other variables associated with the smooth running of the serial subsystem...
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.