As Brian Kernighan, A-W Professional Computing Series Advisor comments, "Henry Spencer is definitely authoritative. He has written a lot of real code that is much used." Generally, just learning a programming language doesn't teach you how to use it well. This is especially true of C, which is an expert's language: it assumes that its users already know what they're doing and don't need help. Programming classes seldom try to impart much more than minimal competence in using a language, since that in itself is hard enough... especially for C, which is notoriously unforgiving of beginners' mistakes. Even books are often tightly focused on getting you competent with the language, and neglect what you might do with it. So even programmers who know C in considerable detail often have only general notions of how to use it well. This book shows how to program well in C, and also how not to, showing examples of both good and bad practice, and explaining why one is preferable over the other.