=== A.12.10 Predefined names ===

Several identifiers are predefined, and expand to produce special information. They, and also the preprocessor expansion operator defined, may not be undefined or redefined.

__LINE__	A decimal constant containing the current source line number.
__FILE__	A string literal containing the name of the file being compiled.
__DATE__	A string literal containing the date of compilation, in the form "Mmmm dd yyyy"
__TIME__	A string literal containing the time of compilation, in the form "hh:mm:ss"
__STDC__	The constant 1. It is intended that this identifier be defined to be 1 only in standard-conforming implementations.

    #error and #pragma are new with the ANSI standard; the predefined preprocessor macros are new, but some of them have been available in some implementations.