Re: The difference between strtol() and strtoul() ?

From	Michael S <already5chosen@yahoo.com>
Newsgroups	comp.lang.c
Subject	Re: The difference between strtol() and strtoul() ?
Date	2024-06-23 15:32 +0300
Organization	A noiseless patient Spider
Message-ID	<20240623153219.000009b0@yahoo.com> (permalink)
References	(2 earlier) <20240621182839.00000dc4@yahoo.com> <20240621185314.00004fda@yahoo.com> <87o77uqktg.fsf@bsb.me.uk> <20240623121952.00005fa9@yahoo.com> <87r0cnq46s.fsf@bsb.me.uk>

Show all headers | View raw

On Sun, 23 Jun 2024 12:38:51 +0100
Ben Bacarisse <ben@bsb.me.uk> wrote:

> Michael S <already5chosen@yahoo.com> writes:
> 
> > On Fri, 21 Jun 2024 18:15:07 +0100
> > Ben Bacarisse <ben@bsb.me.uk> wrote:
> >  
> >> Michael S <already5chosen@yahoo.com> writes:
> >>   
> >> > On Fri, 21 Jun 2024 18:28:39 +0300
> >> > Michael S <already5chosen@yahoo.com> wrote:
> >> >    
> >> >> On Fri, 21 Jun 2024 13:58:01 -0000 (UTC)
> >> >> gazelle@shell.xmission.com (Kenny McCormack) wrote:    
> >> >> > 
> >> >> > Yeah, now I get it.  You really only need strtoimax() and
> >> >> > strtoumax().     
> >> >> 
> >> >> Which are? uunfortunately, not part of C standard.
> >> >>     
> >> >> > A result of any smaller type can be obtained by calling one of
> >> >> > these functions and storing the result in an object of the
> >> >> > smaller type.   
> >> >> 
> >> >> Or check for range and handle out of range values as
> >> >> appropriate by situation.    
> >> >
> >> > BTW, I don't know what The Standard says about out-of-range
> >> > inputs, but at least
> >> > https://en.cppreference.com/w/c/string/byte/strtol does not say
> >> > anything certain. especially about what stored in *str_end.    
> >> 
> >> It says what value should be returned.  That's something certain!
> >>  
> >
> > In case of strtol, yes. 
> > In case of strtoul it also says what value should be returned, but
> > plain reading of cppreference.com text (at least *my* plain reading)
> > does not match observed behaviour. The text on cppreference.com
> > resembles Standard text, but does not match it.  
> 
> Ah.  What's the discrepancy you see?
> 

IMHO, the Standard texts allows for more interpretations (and
misinterpretations) than cppreference.com text 


> > Also, at least to me, Standard text itself appear very far from
> > clear and way too open to interpretations.
> > My own interpretation would be that for any negative input strtoul()
> > should return ULONG_MAX and set errno to ERANGE. None of the actual
> > implementation that I tested behaves in this manner.  
> 
> I don't get that from the text.  There is, after all, no "negative
> input".  There is a "subject sequence" which, if it starts with a
> minus sign, causes the "value resulting from the conversion is
> negated (in the return type)" which seems clear enough.
>

I find it less than clear.
The most non-clear part is that for strtouxx() as long as "subject
sequence" is in range, it is first converted and then negated. However
when  "subject sequence" is out of range it is converted, then clipped
and then *not* negated.
I don't feel confused in the similar way by none-u variants of strtoxx()

> > It seems, the problem is of what is considered "range of
> > representable values" for unsigned type is by itself open to
> > interpretations.
> >
> > IMHO, even if in some part of the standard  there exists text that
> > clearly states that "range of representable values for unsigned
> > long = [-ULONG_MAX:ULONG_MAX]" it is worth repeating that in the
> > section that defines strtol, because it is at all non-intuitive.  
> 
> I don't get what you are saying here.  The range of values is
> [0:ULONG_MAX].
>

That as long as you see sign as something detached from the rest of the
number. I tend to see them as parts of the whole. May be, that's my
mistake.

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

The difference between strtol() and strtoul() ? gazelle@shell.xmission.com (Kenny McCormack) - 2024-06-20 14:06 +0000
  Re: The difference between strtol() and strtoul() ? scott@slp53.sl.home (Scott Lurndal) - 2024-06-20 14:46 +0000
    Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-20 14:37 -0700
  Re: The difference between strtol() and strtoul() ? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-06-20 14:48 +0000
  Re: The difference between strtol() and strtoul() ? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2024-06-20 15:26 +0000
  Re: The difference between strtol() and strtoul() ? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-20 22:55 +0000
    Re: The difference between strtol() and strtoul() ? gazelle@shell.xmission.com (Kenny McCormack) - 2024-06-20 23:35 +0000
  Re: The difference between strtol() and strtoul() ? gazelle@shell.xmission.com (Kenny McCormack) - 2024-06-21 13:58 +0000
    Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-21 18:28 +0300
      Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-21 18:53 +0300
        Re: The difference between strtol() and strtoul() ? scott@slp53.sl.home (Scott Lurndal) - 2024-06-21 16:14 +0000
          Re: The difference between strtol() and strtoul() ? scott@slp53.sl.home (Scott Lurndal) - 2024-06-21 16:54 +0000
            Re: The difference between strtol() and strtoul() ? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-22 06:44 +0000
              Re: The difference between strtol() and strtoul() ? scott@slp53.sl.home (Scott Lurndal) - 2024-06-22 15:16 +0000
                Re: The difference between strtol() and strtoul() ? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-22 23:21 +0000
                Re: The difference between strtol() and strtoul() ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-22 20:10 -0400
        Re: The difference between strtol() and strtoul() ? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-21 18:15 +0100
          Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-23 12:19 +0300
            Re: The difference between strtol() and strtoul() ? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-23 12:38 +0100
              Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-23 15:32 +0300
                Re: The difference between strtol() and strtoul() ? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-23 16:30 +0100
                Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-23 18:47 +0300
                Re: The difference between strtol() and strtoul() ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-23 10:58 -0700
                Re: The difference between strtol() and strtoul() ? scott@slp53.sl.home (Scott Lurndal) - 2024-06-23 21:19 +0000
                Re: The difference between strtol() and strtoul() ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-23 22:28 -0700
                Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-23 16:01 -0700
                Re: The difference between strtol() and strtoul() ? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-24 00:49 +0100
                Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-23 17:49 -0700
                Re: The difference between strtol() and strtoul() ? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-24 02:29 +0000
                Re: The difference between strtol() and strtoul() ? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-24 02:31 +0000
                Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-23 20:12 -0700
                Re: The difference between strtol() and strtoul() ? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-24 06:05 +0000
                Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-23 20:11 -0700
                Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-24 13:19 +0300
                Re: The difference between strtol() and strtoul() ? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-06-23 22:30 -0700
                Re: The difference between strtol() and strtoul() ? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-24 00:48 +0000
        Re: The difference between strtol() and strtoul() ? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-06-21 14:38 -0400
          Re: The difference between strtol() and strtoul() ? gazelle@shell.xmission.com (Kenny McCormack) - 2024-06-21 18:43 +0000
            Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-23 11:47 +0300
          Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-22 21:18 +0300
      Re: The difference between strtol() and strtoul() ? Ben Bacarisse <ben@bsb.me.uk> - 2024-06-21 18:02 +0100
        Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-21 10:38 -0700
          Re: The difference between strtol() and strtoul() ? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-22 06:43 +0000
          Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-22 21:04 +0300
            Re: The difference between strtol() and strtoul() ? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-06-22 23:22 +0000
            Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-22 16:43 -0700
    Re: The difference between strtol() and strtoul() ? Michael S <already5chosen@yahoo.com> - 2024-06-21 19:00 +0300
      Re: The difference between strtol() and strtoul() ? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-06-21 10:50 -0700
    Re: The difference between strtol() and strtoul() ? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-06-22 22:07 +0000
  Re: The difference between strtol() and strtoul() ? Richard Kettlewell <invalid@invalid.invalid> - 2024-06-23 17:39 +0100

csiph-web