ASSERT(3)                  POSIX Programmer's Manual                 ASSERT(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       assert -- insert program diagnostics

SYNOPSIS
       #include <assert.h>

       void assert(scalar expression);

DESCRIPTION
       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.1-2017
       defers to the ISO C standard.

       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.

RETURN VALUE
       The assert() macro shall not return a value.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       abort(), stdin

       The Base Definitions volume of POSIX.1-2017, <assert.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                            ASSERT(3)
