Some useful C libraries guides
- Input/output and file handling: https://www.w3schools.com/c/c_ref_stdio.php
- String: https://www.w3schools.com/c/c_ref_string.php
- Errors: https://www.geeksforgeeks.org/c/error-handling-in-c
- Characters: https://www.w3schools.com/c/c_ref_ctype.php