Is there a way to query AD to find usernames?

Telepathy to the person who entered the names. Otherwise, is "C Smith" Charlie Smith or Charles Smith (uming they're two different people)? There's no way to write code to figure out which totally arbitrary choice some human being made some time in the past. Even writing code to accept a middle initial for a name won't always work. Abby might have been entered as Abagail.