The canonical text on the topic, written by the authors of the language (and Unix). The book is not easy but is slim and direct, pulls no punches, and requires patience and careful study.
It is particularly appropriate for individuals with good programming experience but without extensive C experience.
Beginner programmers may find its pace a little overwhelming.
Ranked in these QuestionsQuestion Ranking
Pro Well known classic
This book is so well known that it's affectionately called "K & R", after the authors.
It's been cited in many other books and is familiar to most, if not all, CS students.
Pro It's excerpted from the idea of its creators
This book is written by Dennis Ritchie, who was one of the main people behind the development and design of C and UNIX.
Pro Creative, challenging exercises
The challenges at the end of each chapter do a great job of requiring many of the skills learned up to that point. Completing the challenges is a great way of insuring you understand the material.
Con Not for beginners
Assumes familiarity not only with programming concepts but some C language specifics.
Con Teaches bad style
The K&R style works for old Unix mainframe command-line programs that exit after a simple task and leave the cleanup to the OS; where input is only from trusted experts; and most functions are only called internally to the program. The environment is very different today. This style will get your server owned by hackers, or crash it due to a memory leak, etc. You will have to unlearn what you've learned from this book to use C correctly in the real world today.
Con Out of Date
Some commands and practices are out of date, so errata and googling is needed while going through the book.