It is written in ruthlessly standard ANSI C (for maximum portability).
It will probably also complement your C -- it's intended to be a handy drop-in scripting language to embed in C programs, though it's also a pretty cool language on its own merits. They had an unwavering focus on keeping it clean and very small for embedding, and they make some really interesting choices along the way. It's sort of like a minimalistic Python; it gets a lot of power out of using "tables" (rather like Python dictionaries or Perl hashes) as a primary data type.
SQLite is always recommended in threads like this (of which, I will point out, there have been several here and at reddit...you might like to search for them). I haven't looked at it since very early releases, but I'm guessing quality has gotten better over time, since it is more stable than ever and faster than ever, and still astoundingly lightweight.
This is probably more than you are looking for, but the fftw code ( www.fftw.org ) is a pretty amazingly designed piece of C code that does some very advanced stuff. However, if you trying to get off to a good start, you might want simplistic examples.
One thing I think helps you become a better programmer, is to read your own code carefully a long time after you have written it.
There's a suggested roadmap for reading it, too: http://www.reddit.com/comments/63hth/ask_reddit_which_oss_co...
It is written in ruthlessly standard ANSI C (for maximum portability).
It will probably also complement your C -- it's intended to be a handy drop-in scripting language to embed in C programs, though it's also a pretty cool language on its own merits. They had an unwavering focus on keeping it clean and very small for embedding, and they make some really interesting choices along the way. It's sort of like a minimalistic Python; it gets a lot of power out of using "tables" (rather like Python dictionaries or Perl hashes) as a primary data type.