Programming in C

It depends on what you're looking for. If you're taking a basic course in C, though, I suspect that a basic text editor would work.

If you're looking for a text editor, I recommend SciTE. You can get it for Linux and Windows, at least. It does context highlighting based on what language you're using, bracket-matching, and a number of other nifty things. It's also a fairly lightweight program that doesn't eat up system resources or overcomplicate the task of simply writing code.

If you're interested in picking up a copy, or just reading more about it, check out the following link:
http://www.scintilla.org/SciTE.html

I use it on Debian GNU/Linux, where it's exceedingly simple to install (simply type "apt-get install scite" at the command line and hit Enter). When I'm forced to work on Windows, I tend to use it fairly heavily there as well (where installation is, like usual, rather more annoying, because it requires downloading and running an installer application, just like with every other piece of software on Windows).

Good luck in your endeavors.