It is always difficult to recommend books for any course and none more so that a C programming course - there are plenty of book to chose from. It is important to get a book that suits your reading style and also provides you with plenty of worked examples.
A suggested reading list is as follows:
Title:The C Programming Language ANSI C Version Author:Kernighan & Ritchie Publisher:Prentice Hall Software Series ISBN:0-13-110362-8
Comment:Ideal reference book and goes well beyond the level of this course. It is expensive but the serious C programmer will kick themself if they don't buy this book.
Title:ANSI C - Made Easy Author:Herbert Schildt Publisher:Osborne McGraw-Hill ISBN:0-07-881500-2 Comment:
Title:Learning to Program in C Author:N. Kantaris Publisher: Babani ISBN:0-85934-203-4 Comment:A good cheap beginners guide.
Title:Illustrating ANSI C Author:Donald Alcock Publisher:Cambridge University Press ISBN:0-521-42483-6 Comment:A good book for the mathematically inclined.
Title:C - The Complete Reference Author:Herbert Schildt Publisher:Osborne McGraw-Hill ISBN:0-07-881263-1 Comment:
Title:Numerical Recipies in C Author:W.H.Press, et al Comment:An advanced level book with, as the name implies, ready-made solutions to your programming problems.