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Re: better atoi

From Joe Pfeiffer <pfeiffer@cs.nmsu.edu>
Newsgroups comp.lang.c
Subject Re: better atoi
Date 2017-02-10 22:01 -0700
Organization A noiseless patient Spider
Message-ID <1bshnliamn.fsf@pfeifferfamily.net> (permalink)
References <853138f9-54d1-435f-90d5-ef75a38e65bf@googlegroups.com> <1b1sv5k98w.fsf@pfeifferfamily.net> <lno9y9vdpy.fsf@kst-u.example.com>

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Keith Thompson <kst-u@mib.org> writes:

> Joe Pfeiffer <pfeiffer@cs.nmsu.edu> writes:
>> fir <profesor.fir@gmail.com> writes:
>>> http://www.cplusplus.com/reference/cstdlib/strtol/
>>>
>>> it is said that strtol sets  errno to ERANGE but is
>>> not mentioned with wrong value, so im not sure if
>>> it can be uniformly checked (probably yest though 
>>> but only not noted (i not checked it though))
>>
>> It says it returns LONG_MAX or LONG_MIN in this case (so it appears it
>> is possible that if the string does in fact represent one of those
>> values, you can't reliably detect the conversion was successful -- as
>> we've seen in other places, we can't rely on ERRNO being 0 on success.
>> We'd sort of hope for it in this function...).
>
> No, if you set errno to 0 before calling strtol() you can rely in it not
> being set to ERANGE unless there's an error.
>
> N1570 7.5p3:
>
>     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.
>
> Since the use of errno *is* documented for strtol(), it can't set it to
> nonzero unless there's an error.  (I suppose you could interpret that
> wording in a way that allows to set errno even if it's successful, but
> that's not a reasonable reading.)

My recollection is that there are functions that do that (though I can't
provide an example that I remember clearly does it -- I want to say
open(), but would be very happy to be wrong).

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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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