I need this for my C++ application. I've never used it before and was wondering if anyone could point me to something good to use that already exists. I need to log some data from the release build since it refuses to crash in debug. Thanks

there are numerous logging classes for c++ out there, which might be the reason no one answers your question.
as i'm a bit of a fan of the boost way of doing things i just wanted to point you at the work john torjo has done with his logging library (which has boost dependencies). (http://www.torjo.com) it follows the boost style and imo is quite nice to use. note, that this is not an official boost library. it has been submitted to the boost review process but has been rejected recently. i wouldn't let this stop me from using it, though. the quality of the library is rather high. boost standards are a little higher ;-) might be right thing for your needs.

if you don't want to use boost just have a look around. there's plenty of logging related stuff out there. and yes, sometimes an entire library is overkill. use what works for you not the wickedest implementation you can find.

cheers,
simon