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Groups > comp.lang.c > #101352

Re: standard error codes

From BartC <bc@freeuk.com>
Newsgroups comp.lang.c
Subject Re: standard error codes
Date 2017-01-09 21:50 +0000
Organization A noiseless patient Spider
Message-ID <o510fi$16v$1@dont-email.me> (permalink)
References (1 earlier) <212f08fd-b09e-4848-8485-f7480eaaae45@googlegroups.com> <bf564370-cac4-4030-8487-893c5ea71ddc@googlegroups.com> <86260b21-0fa2-42b4-93c6-08e9241d4c17@googlegroups.com> <lnk2a4qi1v.fsf@kst-u.example.com> <64011b84-2f8d-44f2-902a-0eacfcdf630b@googlegroups.com>

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On 09/01/2017 17:52, Thiago Adams wrote:
> On Monday, January 9, 2017 at 3:06:31 PM UTC-2, Keith Thompson wrote:
>> Malcolm McLean  writes:
>> [...]
>>> 0 for success, -1 for fail is one of the standard conventions.
>>
>> I think 0 for success, 1 for failure is more common.  Or 0 for success,
>> non-0 for failure.
>>
>
> I guess some standard functions try to use some result
> and adapt it to show errors without to use/create a new
> type for error.
>
> For instance:
>
> char *fgets( char *str, int count, FILE* stream );
>
> Return value
> str on success, null pointer on failure.
>
>
> Using the same logic, for array_push for instance, I could
> return -1 if the element was not added, or return the
> number of elements after insertion.
>
> The same for array_reserve (allocates n elements).

C's zero-based indexing makes it harder to use 0 for failure and N for 
success.

For example, for a routine that searches an array indexed 0 to N-1 for 
the index of some value, 0 must be one of the return values denoting 
success. With a one-based list, then you can't do:

   if (find(A,N,X)) ...

instead if might need to be:

   if (find(A,N,X) != NOTFOUND) ...

or '!= -1' or '>= 0'.

-- 
Bartc

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Thread

standard  error codes Thiago Adams <thiago.adams@gmail.com> - 2017-01-08 06:34 -0800
  Re: standard  error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-08 11:05 -0800
    Re: standard  error codes Thiago Adams <thiago.adams@gmail.com> - 2017-01-09 03:33 -0800
      Re: standard  error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-09 04:55 -0800
        Re: standard  error codes Keith Thompson <kst-u@mib.org> - 2017-01-09 09:06 -0800
          Re: standard  error codes Thiago Adams <thiago.adams@gmail.com> - 2017-01-09 09:52 -0800
            Re: standard error codes BartC <bc@freeuk.com> - 2017-01-09 21:50 +0000
              Re: standard error codes BartC <bc@freeuk.com> - 2017-01-09 22:36 +0000
                Re: standard error codes supercat@casperkitty.com - 2017-01-09 14:51 -0800
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-09 23:39 +0000
                Re: standard error codes supercat@casperkitty.com - 2017-01-09 15:51 -0800
                Re: standard error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-09 16:08 -0800
                Re: standard error codes supercat@casperkitty.com - 2017-01-09 18:51 -0800
                Re: standard error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-10 02:02 -0800
                Re: standard error codes supercat@casperkitty.com - 2017-01-10 07:34 -0800
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-10 01:39 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-10 09:07 -0800
                Re: standard error codes supercat@casperkitty.com - 2017-01-10 09:59 -0800
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-10 12:02 -0800
                Re: standard error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-10 12:53 -0800
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-10 13:03 -0800
                Re: standard error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-10 15:41 -0800
                Re: standard error codes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-01-11 02:56 +0000
                Re: standard error codes supercat@casperkitty.com - 2017-01-11 07:42 -0800
                Re: standard error codes supercat@casperkitty.com - 2017-01-10 12:59 -0800
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-10 18:14 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-10 12:12 -0800
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-10 20:35 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-10 13:00 -0800
                Re: standard error codes supercat@casperkitty.com - 2017-01-11 08:16 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-11 18:25 +0000
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-11 19:09 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-11 12:03 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-11 20:10 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-11 12:19 -0800
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-11 20:31 +0000
                Re: standard error codes Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-01-11 15:32 -0500
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-11 20:48 +0000
                Re: standard error codes Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-01-11 15:58 -0500
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-11 13:01 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-11 21:05 +0000
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-11 21:08 +0000
                Re: standard error codes Gareth Owen <gwowen@gmail.com> - 2017-01-11 21:38 +0000
                Re: standard error codes BartC <bc@freeuk.com> - 2017-01-11 21:58 +0000
                Re: standard error codes David Brown <david.brown@hesbynett.no> - 2017-01-12 12:11 +0100
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-12 09:28 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-12 18:06 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-12 11:39 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-12 19:50 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-12 13:03 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-12 21:13 +0000
                Re: standard error codes <william@wilbur.25thandClement.com> - 2017-01-12 20:00 -0800
                Re: standard error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-13 01:56 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-13 12:54 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-13 09:35 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-13 17:38 +0000
                Re: standard error codes James Kuyper <jameskuyper@verizon.net> - 2017-01-13 13:06 -0500
                Re: standard error codes raltbos@xs4all.nl (Richard Bos) - 2017-01-18 12:00 +0000
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-18 12:13 +0000
                Re: standard error codes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-01-12 16:43 -0800
                Re: standard error codes <william@wilbur.25thandClement.com> - 2017-01-12 19:34 -0800
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-13 09:27 -0800
                Re: standard error codes raltbos@xs4all.nl (Richard Bos) - 2017-01-12 19:33 +0000
                Re: standard error codes Keith Thompson <kst-u@mib.org> - 2017-01-12 12:10 -0800
                Re: standard error codes supercat@casperkitty.com - 2017-01-11 11:50 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-11 20:38 +0000
                Re: standard error codes jadill33@gmail.com - 2017-01-11 12:26 -0800
                Re: standard error codes Richard Heathfield <rjh@cpax.org.uk> - 2017-01-11 20:44 +0000
      Re: standard  error codes Keith Thompson <kst-u@mib.org> - 2017-01-09 09:03 -0800
  Re: standard  error codes supercat@casperkitty.com - 2017-01-08 11:40 -0800

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