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Re: better atoi

From Ben Bacarisse <ben.usenet@bsb.me.uk>
Newsgroups comp.lang.c
Subject Re: better atoi
Date 2017-02-12 02:16 +0000
Organization A noiseless patient Spider
Message-ID <87d1eow3tx.fsf@bsb.me.uk> (permalink)
References (5 earlier) <1bbmu8isvo.fsf@pfeifferfamily.net> <877f4wy6xt.fsf@bsb.me.uk> <1blgtc5piu.fsf@pfeifferfamily.net> <87inogwd09.fsf@bsb.me.uk> <1b8tpc5gdc.fsf@pfeifferfamily.net>

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Joe Pfeiffer <pfeiffer@cs.nmsu.edu> writes:

> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>
>> Joe Pfeiffer <pfeiffer@cs.nmsu.edu> writes:
>>
>>> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>>>
>>>> Joe Pfeiffer <pfeiffer@cs.nmsu.edu> writes:
>>>>
>>>>> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>>>>>
>>>>>> Joe Pfeiffer <pfeiffer@cs.nmsu.edu> writes:
>>>>>>
>>>>>>> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>>>> <snip>
>>>>>>>>   "The value of errno [...] is zero at program startup [...], but is
>>>>>>>>   never set to zero by any library function.  The value of errno may be
>>>>>>>>   set to nonzero by a library function call whether or not there is an
>>>>>>>>   error, provided the use of errno is not documented in the description
>>>>>>>>   of the function in this International Standard."
>>>>
>>>> <snip>
>>>>> As I remember the situation, the documentation required is a
>>>>> statement saying the function *doesn't* set errno unless there is an
>>>>> error.
>>>>
>>>> I must be rather dense to day because I just don't get what you are
>>>> saying.  Can you give an example of either some documentation or a code
>>>> fragment that does not comport with that quote above from the standard?
>>>
>>> As Keith pointed out, my standard example of a function that can screw
>>> up errno in spite of success, open(), isn't actually defined in the C
>>> standard (it's in POSIX), so it isn't strictly relevant after all...
>>
>> So would fopen be an example of what you mean?  fopen is a standard
>> function and many implementations of fopen have it set errno.  The errno
>> setting is essential for good diagnostics in many systems.
>
> If it can set errno in spite of being successful, yes.

No library function may set errno to zero but I think you mean if fopen
can set errno to a non-zero in spite of being successful.  If that is
what you meant then let's assume that such a fopen exists.

Are you saying that an fopen like that (which, let's say, sets errno to
42 on success) is in some way wrong or problematic?

-- 
Ben.

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better atoi fir <profesor.fir@gmail.com> - 2017-02-10 12:24 -0800
  Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-10 12:35 -0800
  Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 14:48 -0700
    Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-10 14:12 -0800
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:36 -0700
        Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-11 01:07 -0800
          Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 10:10 -0700
            Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-11 09:26 -0800
              Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 15:36 -0700
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 00:18 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 00:31 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 03:47 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 04:22 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 06:08 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 06:13 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 07:31 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:02 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:08 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:17 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 08:23 -0800
                Re: better atoi Robert Latest <boblatest@yahoo.com> - 2017-02-19 11:11 +0000
            Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 17:33 +0000
              Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 15:35 -0700
                Re: better atoi "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-11 17:52 -0500
                Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 18:53 -0700
    Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-10 22:50 +0000
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 21:59 -0700
        Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 12:08 +0000
          Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 09:39 -0700
            Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 17:26 +0000
              Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 15:30 -0700
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-11 22:58 +0000
                Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-11 18:48 -0700
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-12 02:16 +0000
                Re: better atoi "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-12 09:57 -0500
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 07:27 -0800
                Re: better atoi jameskuyper@verizon.net - 2017-02-12 08:44 -0800
                Re: better atoi fir <profesor.fir@gmail.com> - 2017-02-12 09:15 -0800
                Re: better atoi Malcolm McLean <malcolm.mclean5@btinternet.com> - 2017-02-12 09:44 -0800
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-12 18:32 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-12 18:56 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-12 19:18 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-13 00:16 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-13 01:56 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-13 10:44 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-13 11:38 +0000
                Re: better atoi Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-02-13 14:37 +0000
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-13 15:00 +0000
                Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-12 11:15 -0800
                Re: better atoi BartC <bc@freeuk.com> - 2017-02-12 19:25 +0000
                Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-12 11:54 -0800
                Re: better atoi supercat@casperkitty.com - 2017-02-12 13:13 -0800
    Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-10 15:16 -0800
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:01 -0700
        Re: better atoi Keith Thompson <kst-u@mib.org> - 2017-02-11 01:30 -0800
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:26 -0700
    Re: better atoi Nick Bowler <nbowler@draconx.ca> - 2017-02-11 00:26 +0000
      Re: better atoi Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-02-10 22:32 -0700
    Re: better atoi "James R. Kuyper" <jameskuyper@verizon.net> - 2017-02-19 11:10 -0500

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