K&R is so clearly written that I was able to understand it as a sixth grader. (At least, I felt like I did; subsequent events later proved that I did not understand pointers, but I don't think it was K&R's fault that a sixth grader didn't understand.) That's why it's still being recommended and the much thicker tomes also purporting to teach the C language have been forgotten. It's probably the same reason that your copy is torn and tattered.

I don't share your opinion and most people I know that do C do not share it also. It's good base to get familiar with language, no one say you can't expand your knowledge further after reading this book.

I've read some other "modern" books about C like "21st century C" but they are not for people that do not know C and they are not so good for people that know it.

Can you provide any arguments to support what you wrote? What alternative you would propose for learning C?

https://www.amazon.com/Programming-Language-Brian-W-Kernigha...

Read what majority of opinions say. It's really easy to criticize without giving better alternative.

Keep in mind that I and the parent were mostly discussing C++, a very different language from C.