The following internet resources provide information related to developing and maintaining software in the C and C++ languages.
While the net contains info on the on-going evolution of the C language, the actual ANSI C language specification (INCITS/ISO/IEC 9899-1999) is available as a .pdf download. You can order it from ANSI or from INCITS, where a printed version is also available.
Among the on-line language reference sites are:
Like that for C, the ANSI C++ language specification (ISO/IEC 14882:2011) is available as a .pdf file. You can order it from ANSI or from INCITS, where a printed version is also available.
C++ language reference sites include:
In the spirit of standing on the shoulders of those who have come before, here are some source code repositories. While SourceForge.net and freshmeat are the standard open source repositories, here are some other potential sources for generally well-tested and portable source code and algorithms.
netlib collection of mathematical software (Dongarra and Grosse)
There are a number of issues specific to using C and C++ in embedded environments. Of course, the manual for your specific compiler is a critical reference. Here are some other resources that focus on firmware development.