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From: Michael S <already5chosen@yahoo.com>
Newsgroups: comp.lang.c
Subject: Re: The difference between strtol() and strtoul() ?
Date: Sun, 23 Jun 2024 12:19:52 +0300
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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. 
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.
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.