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 depend-
       ing 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 3.25 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)