assert.h - verify program assertion
The <assert.h> header shall define the assert() macro. It refers to
the macro NDEBUG which is not defined in the header. If NDEBUG is
defined as a macro name before the inclusion of this header, the
assert() macro shall be defined simply as:
#define assert(ignore)((void) 0)
Otherwise, the macro behaves as described in assert().
The assert() macro shall be redefined according to the current state of
NDEBUG each time <assert.h> is included.
The assert() macro shall be implemented as a macro, not as a function.
If the macro definition is suppressed in order to access an actual
function, the behavior is undefined.
The following sections are informative.
The System Interfaces volume of IEEE Std 1003.1-2001, assert()
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 .