Snow Leopard terminal command problem

I'm working my way through a book on C programming fro the Mac, and right now, I'm trying to compile a simple program. The command in the book is

cc -o slasher main.c

but the terminal says

-bash: cc: command not found

I also tried gcc, with the same result. What's the correct command to compile a program from the CLI? The book hasn't yet been updated for OS 10.6

You need to install the developer tools. You can do so either from your OS X Install Disc or from Apple's Web site.

I thought I already had them. I was right, and wrong; I had Xcode, but not the UNIX developer's tools. I installed the extras and the commands worked.