C: A Reference Manual (4th Edition)
You can find bigger books about C, but you won't find one as authoritative or helpful as this reference manual. Harbison and Steele have now gone through four editions and are beginning to cover language differences which can surprise the experienced C coder moving to C++.  As always, the authors do an excellent job of explaining what's standard and what it replaces. No hairy syntax has been omitted, so this volume can make wending one's way through obfuscated code, if not pleasant, at least less miserable. Whether you learned C from Kernighan or some massive tome, you'll want this volume as your day-to-day reference. And you won't mind buying a new edition once in a while, because you'll have worn the old one out by then.