This chapter documents areas specific to the C compiler. The information is organized into language extensions and the environment.
The C compiler is compatible with some of the features of the C language described in the new ISO C standard, ISO/IEC 9899:2011. If you need to compile code that is compatible with the previous C standard, ISO/IEC 9899:1999, use -std=c99. If you need to compile code that is compatible with the ISO/IEC 9899:1990 C standard (and amendment 1), use -std=c89.