How would I go about compiling a C++ program under Windows(or Ubuntu if need be) for a Mac? I use Code::Blocks if it matters at all.

Uh, any C++ compiler should work, you just need to know how to program FOR a Mac..

What? Kellimus, plz leave

The only thing correct about what you said is that system specific commands will not work for the Mac.
Google is your friend: http://forums.macrumors.com/showthread.php?t=180022

I don't know. Also this isn't a very desirable thing. If you plan on developing for multiple platforms it's really best to get some kind of access to those platforms to do testing.

You could always run the platforms in a Platform virtualiser like VMware.

I misread what he said