The GNU C Reference Manual
The GNU C Reference Manual is a reference for the C programming language, as implemented by the GNU C Compiler.
This manual is strictly a reference, not a tutorial. Its aim is to cover every linguistic construct in GNU C, but not the library functions (which are documented elsewhere). This manual would probably not make a good introductory book for new programmers, although those who know languages other than C should be able to learn C using it.
The v0.2.3 release of the manual is now available, which includes a number of corrections suggested by readers, and for the first time ever, a Makefile! (Wow!) If you don't feel like building the manual from the Texinfo source, you can also read an HTML version or a PDF version of the manual.
For additional information, please see the manual's project page at Savannah.