assert

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 output and terminates the program by calling abort() 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
       ISO9899  (ANSI  C).  In the 1990 standard, expression is required to be
       of type int and undefined behavior results if it is  not,  but  in  the
       1999 standard it may have any scalar type.

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

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



C99                               2002-08-25                         ASSERT(3)