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 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

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