Robert Martin "Clean Code" (not going to be original here
)
This programming book will tell you not only how to write good code, but also how to turn bad code into good code. It will help you understand why little things like naming variables correctly are not even little things, but important points on the way to knowing how to write "clean code".
Steve McConnell "Code Complete"
This programming book is something every programmer should read at least once in his or her life. For more than a decade, the first edition was rightly considered the best practical guide to coding. Based on his experience, the author has collected different techniques and programming principles. A programmer of any field, at any level, is sure to find something he or she didn't know or didn't think about before.
Brian Wilson Kernighan "The C Programming Language" (or simply K&R)
A book on programming from the authors of the C language. It became a kind of classic textbook on the C language and is still a classic for everyone who learns and/or uses both C and C++. The book is currently being republished for the third time due to the changes in terminology since then.
However, I wouldn't recommend it for beginners, you'll need at least some basic understanding of the programming universe.