As other have noted, pick up a copy of this book https://en.wikipedia.org/wiki/The_C_Programming_Language it was written by the two guys that created C (and also contributed quite a bit to UNIX). Its perhaps one of the truly "original" programing textbooks (and it does not have some wacky animal on the front). The creator of C++ also has written many books on the topic https://www.stroustrup.com/books.html all that are pretty decent.

If you want to lean by doing my advice is to get an arduino and try and build stuff. The arduino has a C like language (and will also accept C code) which is a great way to learn the language with fun projects. More importantly it will force you to learn C in a very restricted environment where you actually have to think about clock speed, memory management and code efficiency due to the micro controllers limited resources.