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From: CBFalconer <cbfalconer AT yahoo DOT com>
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Subject: Re: Fibonacci number
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Date: Tue, 24 Feb 2004 14:15:43 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Hans-Bernhard Broeker wrote:
> 
> DJ Delorie <dj AT delorie DOT com> wrote:
> 
> > >   [#4] The subject sequence is defined as the longest  initial
> > >   subsequence  of  the  input  string, starting with the first
> > >   non-white-space character, that is  of  the  expected  form.
> 
> > ISO 9899/1999 explicitly allows '-' to be part of the expected form
> > for strtoul.
> 
> So does C89.  It explicitly mentions both signs and digits as allowed
> characters in the subject sequence.
> 
> > Ok, *that* is a bug.  Amusingly enough, glibc 2.3.2 has the same bug.
> 
> I don't it's a bug.  Not unless they changed this between C89 and C99.
> ISO C90 section 7.10.1.6 (strtoul), paragraph 5 says:
> 
>   If the subject sequence begins with a minus sign, the value resulting
>   from the conversion is negated.
> 
> Since negation is a well-defined operation on unsigned longs, there's
> no error involved.  In other words: strtoul on "-1" will result in
> ULONG_MAX not because an error was detected, but because ULONG_MAX is
> the correct result of

Which makes the whole matter moot, since the existing code meets
that standard.  It is not the first standard provision of which I
disapprove :-)

-- 
Chuck F (cbfalconer AT yahoo DOT com) (cbfalconer AT worldnet DOT att DOT net)
   Available for consulting/temporary embedded and systems.
   <http://cbfalconer.home.att.net>  USE worldnet address!