Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary?

From	Andrey Tarasevich <noone@noone.net>
Newsgroups	comp.lang.c++
Subject	Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary?
Date	2025-02-15 16:21 -0800
Organization	A noiseless patient Spider
Message-ID	<vorb2t$8io0$1@dont-email.me> (permalink)
References	<8463694f3a751b287c857fca181451f36eeee982.camel@gmail.com>

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On Tue 11/19/2024 7:02 PM, wij wrote:
> EXIT_SUCCESS/EXIT_FAILURE are for communication between different programs.
> But, is it necessary? E.g. can it be put into shell script?
> I think the macro EXIT_SUCCESS/EXIT_FAILURE may be good within a group of
> programs for some reason, but generally, exit code of program is a numerical
> value. Why EXIT_SUCCESS?

On can point out that `EXIT_SUCCESS` is "not necessary" in exactly the 
same way macro `NULL` is "not necessary".

The language spec explicitly states that every time you do return `0` 
from `main`, the actual value returned to the hosting environment is the 
environment-specific "success" value. It means that when you do `return 
0`, it does not mean that integer `0` is actually returned to the host 
(even on systems that support integral returns). The environment might 
actually receive `1`, `42`, `255`, `3.14` or "ok". The implementation is 
required to _translate_ the value. And the process of translation of `0` 
into the appropriate "success value" in return-from-main contexts takes 
place outside of `EXIT_SUCCESS` macro. Regardless of how `EXIT_SUCCESS` 
is defined, you can always return `0` instead of returning 
`EXIT_SUCCESS` and get the same effect. Implementations are free to 
define `EXIT_SUCCESS` as something different from `0`, but there's no 
need to since defining it as `0` will always work anyway.

This is very similar to `NULL`: you can always use `0` in place of 
`NULL`, and while it is possible to define `NULL` as something different 
from `0`, defining it as `0` will always work anyway. So, is `NULL` 
necessary or unnecessary?

Meanwhile, `EXIT_FAILURE` is different, since there's no translation 
mechanism for non-zero return values. And this might hint at one reason 
for `EXIT_FAILURE`'s existence: since the "success" value is not 
necessarily zero (on the host's side), using an arbitrary non-zero value 
as a "failure" value might result in an unintended collision with 
devastating consequences. For example, the host might use integer 255 as 
the "success" value (meaning that `return 0` will actually result in 255 
being returned to the host), whilst the program's author might 
unknowingly employ 255 as indicator of some specific error. If 
non-translated integer 255 ends up returned to the host, the host will 
see it as a success value. This is where `EXIT_FAILURE` comes in. 
`EXIT_FAILURE` is there to provide you with _at_ _least_ _one_ return 
value that _definitely_ does not collide with "success" value on the 
host's side.

So, `EXIT_SUCCESS` is not necessary, aside from providing 
optimistically-sounding mnemonic. `EXIT_FAILURE` is kinda necessary... 
albeit it provides the kind of portability that is usually left 
unrequested in practice.

-- 
Best regards,
Andrey

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Is EXIT_SUCCESS/EXIT_FAILURE necessary? wij <wyniijj5@gmail.com> - 2024-11-20 11:02 +0800
  Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Paavo Helde <eesnimi@osa.pri.ee> - 2024-11-20 09:22 +0200
    Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastartdlyHQ.org - 2024-11-20 08:27 +0000
      Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-20 13:47 +0000
        Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastartdlyHQ.org - 2024-11-20 15:05 +0000
          Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-20 15:45 +0000
            Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastartdlyHQ.org - 2024-11-20 16:41 +0000
    Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-11-20 13:37 -0800
      Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-20 22:11 +0000
        Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-11-20 14:33 -0800
          Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-20 23:03 +0000
            Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-11-20 15:57 -0800
          Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-11-20 15:58 -0800
            Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-21 13:43 +0000
              Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastartdlyHQ.org - 2024-11-21 16:07 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-21 17:55 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? David Brown <david.brown@hesbynett.no> - 2024-11-22 09:30 +0100
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Ross Finlayson <ross.a.finlayson@gmail.com> - 2024-11-22 11:10 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@dastardlyhq.com - 2024-11-23 11:36 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-11-22 12:26 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-11-22 12:49 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-22 23:26 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? David Brown <david.brown@hesbynett.no> - 2024-11-23 13:07 +0100
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-11-25 13:55 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-01 20:57 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastartdlyHQ.org - 2024-11-22 09:55 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-11-26 04:21 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-22 11:57 -0500
              Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-22 11:31 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-11-22 12:36 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-22 16:53 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? wij <wyniijj5@gmail.com> - 2024-11-24 12:57 +0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-11-25 14:03 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? wij <wyniijj5@gmail.com> - 2024-11-26 12:21 +0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? wij <wyniijj5@gmail.com> - 2024-11-27 16:23 +0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastartdlyHQ.org - 2024-11-27 08:26 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? wij <wyniijj5@gmail.com> - 2024-11-27 18:48 +0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Paavo Helde <eesnimi@osa.pri.ee> - 2024-11-27 15:39 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-27 13:54 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-27 17:24 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-27 16:12 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Richard Damon <richard@damon-family.org> - 2024-11-27 13:00 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-28 08:23 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-28 15:06 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Richard Damon <richard@damon-family.org> - 2024-11-28 08:08 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-27 14:58 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Ross Finlayson <ross.a.finlayson@gmail.com> - 2024-11-27 19:46 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-28 08:26 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Paavo Helde <eesnimi@osa.pri.ee> - 2024-11-28 13:03 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Ralf Fassel <ralfixx@gmx.de> - 2024-11-28 12:15 +0100
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Paavo Helde <eesnimi@osa.pri.ee> - 2024-11-28 13:36 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Ralf Fassel <ralfixx@gmx.de> - 2024-11-28 14:12 +0100
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Richard Damon <richard@damon-family.org> - 2024-11-28 07:50 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-28 15:19 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-28 15:12 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-28 17:36 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? David Brown <david.brown@hesbynett.no> - 2024-11-28 16:43 +0100
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-28 15:59 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Ross Finlayson <ross.a.finlayson@gmail.com> - 2024-11-28 10:19 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Paavo Helde <eesnimi@osa.pri.ee> - 2024-11-28 22:41 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-29 00:21 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Paavo Helde <eesnimi@osa.pri.ee> - 2024-11-29 00:59 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-29 01:20 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-28 17:18 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Paavo Helde <eesnimi@osa.pri.ee> - 2024-11-27 19:01 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-28 08:22 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Ross Finlayson <ross.a.finlayson@gmail.com> - 2024-11-27 11:00 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-27 14:57 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Muttley@DastardlyHQ.org - 2024-11-27 13:52 +0000
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-27 14:54 -0500
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-28 15:27 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-27 15:30 +0200
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-11-28 18:32 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-11-25 14:00 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-11-25 14:15 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-12-01 21:00 -0800
                Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-11-26 04:26 -0800
          Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-20 23:20 -0500
        Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Ross Finlayson <ross.a.finlayson@gmail.com> - 2024-11-20 17:32 -0800
          Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? red floyd <no.spam.here@its.invalid> - 2024-11-20 22:56 -0800
            Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-21 13:52 +0000
          Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-21 13:51 +0000
  Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-20 13:44 +0000
    Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? wij <wyniijj5@gmail.com> - 2024-11-20 22:57 +0800
      Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Michael S <already5chosen@yahoo.com> - 2024-11-20 17:23 +0200
  Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-11-20 23:09 -0500
    Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? scott@slp53.sl.home (Scott Lurndal) - 2024-11-21 13:52 +0000
    Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? wij <wyniijj5@gmail.com> - 2024-11-21 22:45 +0800
  Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Rosario19 <Ros@invalid.invalid> - 2024-11-25 22:20 +0100
    Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? "Fred. Zwarts" <F.Zwarts@HetNet.nl> - 2024-11-26 10:20 +0100
      Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Rosario19 <Ros@invalid.invalid> - 2024-11-30 16:52 +0100
  Re: Is EXIT_SUCCESS/EXIT_FAILURE necessary? Andrey Tarasevich <noone@noone.net> - 2025-02-15 16:21 -0800

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