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From:	Hans-Bernhard Broeker <broeker AT physik DOT rwth-aachen DOT de>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Fibonacci number
Date:	24 Feb 2004 13:12:22 GMT
Organization:	Aachen University of Technology (RWTH)
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To:	djgpp AT delorie DOT com
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Reply-To:	djgpp AT delorie DOT com

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

	 -(1UL)

-- 
Hans-Bernhard Broeker (broeker AT physik DOT rwth-aachen DOT de)
Even if all the snow were burnt, ashes would remain.

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