Yolinux.com

assert manpage

Search topic Section


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



NAME
       assert - abort the program if assertion is false

SYNOPSIS
       #include <assert.h>

       void assert(scalar expression);

DESCRIPTION
       If  the	macro  NDEBUG  was  defined  at the moment <assert.h> was last
       included, the macro assert() generates no code, and hence does  nothing
       at all.	Otherwise, the macro assert() prints an error message to stan-
       dard error and terminates the program by calling abort(3) if expression
       is false (i.e., compares equal to zero).

       The  purpose  of	 this  macro is to help programmers find bugs in their
       programs.  The  message	"assertion  failed  in	file  foo.c,  function
       do_bar(), line 1287" is of no help at all to a user.

RETURN VALUE
       No value is returned.

ATTRIBUTES
       For   an	  explanation	of   the  terms	 used  in  this	 section,  see
       attributes(7).

       +----------+---------------+---------+
       |Interface | Attribute	  | Value   |
       +----------+---------------+---------+
       |assert()  | Thread safety | MT-Safe |
       +----------+---------------+---------+

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, C89, C99.  In C89, expression  is  required
       to  be  of type int and undefined behavior results if it is not, but in
       C99 it may have any scalar type.

BUGS
       assert() is implemented as a macro; if the expression tested has	 side-
       effects, program behavior will be different depending on whether NDEBUG
       is defined.  This may create Heisenbugs which go away when debugging is
       turned on.

SEE ALSO
       abort(3), assert_perror(3), exit(3)

COLOPHON
       This  page  is  part of release 4.04 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       http://www.kernel.org/doc/man-pages/.



GNU				  2015-08-08			     ASSERT(3)