Section: POSIX Programmer's Manual (3P)
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
--- insert program diagnostics
void assert(scalar expression);
The functionality described on this reference page is aligned with the
ISO C standard. Any conflict between the requirements described here and the
ISO C standard is unintentional. This volume of POSIX.1-2008 defers to the ISO C standard.
macro shall insert diagnostics into programs; it shall expand to a
expression. When it is executed, if
(which shall have a
type) is false (that is, compares equal to 0),
shall write information about the particular call that failed on
and shall call
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
and of the identifier __func__.
Forcing a definition of the name NDEBUG,
either from the compiler command line or with the preprocessor control
NDEBUG ahead of the
statement, shall stop assertions from being compiled into the program.
macro shall not return a value.
No errors are defined.
The following sections are informative.
The Base Definitions volume of POSIX.1-2008,
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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
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