ANSI-C Reference Manual (PDF) by Dennis M. Ritchie, the original developer of C back in 1972. A concise manual only for the C language itself as implemented on the PDP-11. However, hints are given occasionally in the text of implementation-dependent features. Although based on PDP-11 implementation, it nevertheless remains useful.
Recommended C Style and Coding Standards (PDF) by L.W. Cannon et al. This document is an updated version of the Original Indian Hill C Style and Coding Standards. It describes a recommended coding standard for C programs. The scope is coding style, not functional organization.
C Traps and Pitfalls (PDF) by Andrew Koenig. The C language is like a carving knife: simple, sharp, and extremely useful in skilled hands. Like any sharp tool, C can injure people who don't know how to handle it. This paper shows some of the ways C can injure the unwary, and how to avoid injury.
Other books (PDF) that will help you to write fast, efficient C code.
Check the ASCII character set when you need to input a special printable character into a string. Ab
Lookup... All ASCII characters, HTML character codes, Extended ASCII, Unicode and more (offsite)
MS-DOS command index. If you are studying this course on a machine with MS-DOS or Windows, these commands can be called from within your C program using the system() command. For example, system("dir > dir.txt"); will list the files in the current directory and store the information in the file "dir.txt". (offsite)
Dictionary of Algorithms and Data Structures produced by the National Institute of Science and Technology, an agency of the U.S. Commerce Department's Technology Administration. This is the place to look first if you don't understand any term. (offsite: NIST)
