How to Write Function-Like Preprocessor Macros (www.youtube.com)
How I program C (www.youtube.com)
How to get an IP address from a host name? (Example in C) (invidious.privacydev.net)
a simple hash table in C (theleo.zone)
Explanation of Quake III's fast inverse square algorithm (www.youtube.com)
Beej's Guide to C Programming (beej.us)
This is a really well-written guide. Covers a ton of concepts in C. (Scroll up for the ToC)....