“The C Programming Language, Second Edition” is an excellent book for learning the basics of ANSI C. However, there have been a few revisions of the C standard since then. While none of the changes are extreme (it’s not like learning Java 1.2 or Python 2 in 2023, and there are many ANSI C code bases still being maintained today), it’s still good to know of the newer features of the language. Additionally, the book does not cover certain pitfalls that affect the security and reliability of programs written in C, such as security problems caused by faulty uses of gets() and strcpy().
It’s unfortunate Dennis Ritchie is no longer with us; it would be nice to have a third edition of K&R that covers modern C standards and has information about best practices for avoiding situations that can lead to insecure code.