[eu90h]

I'd recommend Ben Klemens' excellent book "21st Century C - Tips from the New School" [0]. This book teaches you modern C techniques and, most importantly, the tooling that modern C programmers use (git, autotools, valgrind, etc.) It also covers commonly used libraries to help you from reinventing the wheel (GLib, POSIX standard, SQLite, libxml, & cURL.)

As mentioned in another post, David Hanson's "C Interfaces and Implementations - Techniques for Creating Reusable Software" [1] is a great book, stressing the design of good APIs. This book in particular might help you in your goal to become a better engineer.

On the free side, there's an excellent PDF by Jens Gustedt, "Modern C" [2]. I've not read the whole thing but it seems like an in-depth look at C11.

John Regehr's blog "Embedded in Academia" [3] is a good resource for C programming. You'll learn a lot about weird edge cases and undefined behavior. He also has a recent post about teaching C, with suggestions for resources [4].

[0] https://www.amazon.com/21st-Century-Tips-New-School/dp/14919...

[1] https://www.amazon.com/Interfaces-Implementations-Techniques...

[2] http://icube-icps.unistra.fr/img_auth.php/d/db/ModernC.pdf

[3] http://blog.regehr.org/

[4] http://blog.regehr.org/archives/1393