NAME

       assert - abort the program if assertion is false

SYNOPSIS

       #include <assert.h>

       void assert(scalar expression);

DESCRIPTION

       This macro can help programmers find bugs in their programs, or handle exceptional cases via a crash that
       will produce limited debugging output.

       If expression is false (i.e., compares equal to zero), assert() prints an error message to standard error
       and  terminates  the  program  by  calling abort(3).  The error message includes the name of the file and
       function containing the assert() call, the source code line number of the  call,  and  the  text  of  the
       argument; something like:

           prog: some_file.c:16: some_func: Assertion `val == 0' failed.

       If  the  macro NDEBUG is defined at the moment <assert.h> was last included, the macro assert() generates
       no code, and hence does nothing at all.  It is not recommended to define  NDEBUG  if  using  assert()  to
       detect error conditions since the software may behave non-deterministically.

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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GNU                                                2017-09-15                                          ASSERT(3)