K&R is now free! #C #programming
https://archive.org/details/CProgrammingLanguage2ndEditionByBrianW.KernighanDennisM.Ritchie
This really is a great book, anyone who does any sort of programming should read it. It's not very long but really gives you an understanding of the fundamentals of C.
@Slackwise Sorry, this got lost in my notifications, that post was more popular than I thought it would be!
The honest answer is I don't know. You'll probably disagree but I'd put security in a more advanced category than fundamentals, but then I'm not a developer.
@benofbrown I guess as a starting book, it could still be useful, but there are many books that would service someone better if they're trying to learn modern C that avoids many of the security pitfalls in the language.