C Interfaces and Implementations: Techniques for Creating Reusable Software Book

Easily one the top three books on C that I know about. The author builds what amounts to a "Commons" library of code for C, and does this step by step, explaining every single detail through the use of Literate Programming. It's almost like sitting next to a master programmer as he explains what he's doing, the rationale behind every single decision.

On the downside, it does tend to become a little bit repetitive at times, especially when similar methods are written for different modules, such as, say, put()-like operations for stacks, sets and/or rings.

Nevertheless, this book is a must-read for any C programmer who claims to take his craft seriously. The last chapter on implementing threads is worth the book's price alone.