Beej's Guide to C Programming
This is a really well-written guide. Covers a ton of concepts in C. (Scroll up for the ToC).
There are other formats here https://beej.us/guide/bgc/
https://beej.us/guide/bgc/html/#forewordOpen linkView original on lemmy.blahaj.zone
yeee beej is the best
This guide is incredible. I would've dodged so many pitfalls with binary IO if I had had something like this on hand when I first started programming, haha.