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 standard 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 the programmer find bugs in his program.  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.

CONFORMING TO
       POSIX.1-2001, 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 3.53 of the Linux man-pages project.  A description of the
       project,    and    information    about    reporting    bugs,    can    be    found     at
       http://www.kernel.org/doc/man-pages/.



GNU                                         2002-08-25                                  ASSERT(3)