The C programming exercise book is the "The C Answer Book" by Clovis Tondo and Scott Gimpel. These are the solutions to the challenges from the C programming book.
Book: The C Answer Book: Solutions to the Exercises in 'The C Programming Language,' 2nd Edition
Authors: Clovis L. Tondo, Scott E. Gimpel
Standard: ANSI C
Since Kernighan and Ritchie didn't give the answers to any of the exercises in their book "C Programming Language", Clovis Todo and Scott Gimpel filled that gap. In this book they gave us example implementations for each of the challenges that were left in the original book.
The C programming exercise book follows the spirit of the original - they give you solutions that use only the material covered in previous chapters of the book(meaning no shortcuts using functions from the standard library and other concepts from the next chapters). And this is key. The idea of following a book like this is to learn. Meaning, you should spend a lot more time thinking about the problems, using your creativity, compared to the time you spend reading theory.
Because no one has become a programmer by reading alone!
But the most important part are not the solutions themselves, but the detailed explanations to each exercise. They give you true insights to ANSI C and how to apply the knowledge from the chapters.
Of course, typical for programming - every task can be done in various ways. If your solution does not match the one presented in this book, it does not necessarily mean that you did it wrong. However, you should read carefully why the authors suggest their approach, more often than not, there is a good reason for that.
Note that, just like the K&R's book, this one uses ANSI C(in fact in 1988 the standard was not official yet). But I have to say these 2 books didn't really get old, rather they aged like wine and became classics :)
This book is a great complement to the "C programming Language". If you already have that, the C programming exercise book will be very useful - it provides excellent explanations to the exercises.
However, the book is less useful on its own.
If you are looking for a compilation of programming challenges, consider the Programming Challenges book instead. It also contains material to help you get better at solving algorithmic problems and become a better programmer as a whole.