The assert() macro shall insert diagnostics into programs; it shall
expand to a void expression. When it is executed, if expression
(which shall have a scalar type) is false (that is, compares equal to
0), assert() shall write information about the particular call that
failed on stderr and shall call abort().
The information written about the call that failed shall include the text of the
argument, the name of the source file, the source file line number, and the
name of the enclosing function; the latter are, respectively, the values of
the preprocessing macros __FILE__ and __LINE__ and of the identifier __func__.
Forcing a definition of the name NDEBUG, either from the compiler command line
or with the preprocessor control statement #define NDEBUG ahead of the
#include<assert.h> statement, shall stop assertions from
being compiled into the program.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html