He asked me to implement strcpy(). He thought it was strcpy(from, to) - it's strcpy(to, from).

Interesting. I bet a big part of your win was not just that you were right, but that you conveyed your disagreement without being a d*ck about it. That's a lot harder than being right.

True enough. I just pointed to the K&R on his bookcase and said "Look it up".