[markbnj]

Heh, I got rejected once, a long time ago, for almost exactly this. I was asked to whiteboard a C function to convert an ascii character to an integer, and I wrote one that just returned the result of atoi(). I thought it showed knowledge of the best way to get the job done, but I guess they disagreed.

[vinkelhake]

How does a rejection like that work in practice? Was that the question the interview hinged on?

A reasonable interviewer could just say "Alright, now can you do it without using the standard library?".

[markbnj]

I should be clearer. They didn't specifically reject me for that. There was just a sense that the interview wasn't going well from that point forward. They may just have felt that their request was clear and my response was smart-assed, and in truth that is probably fair.