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Date: Tue, 24 Feb 2004 16:44:50 -0600
From: Eric Rudd <rudd AT cyberoptics DOT com>
Subject: Re: strtoul bug (was Re: Fibonacci number)
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CBFalconer wrote:

>First I think we need a consensus as to what is in error.  I have
>posted something very similar to c.l.c and c.std.c to see what
>appears.  I still consider the acceptance of signs in the unsigned
>varieties to be an error,
>
7.20.1.4, paragraph 3 in the C99 standard specifies the convertible part 
of the input string to consist of "a sequence of letters and 
digits...optionally preceded by a plus or minus sign", so signs appear 
to be acceptable.  Even if the objection is made that strtoul("-1", 
NULL, 10) doesn't lie within the representable range of an unsigned 
long, then the value of strtoul("-0", NULL, 10) surely does, in spite of 
its minus sign.

For me, the question whose answer is most unclear is about the proper 
thing to do when the string represents a number that is out of range.  
 From a reading of 7.20.1.4, it appears to me that ULONG_MAX should be 
returned, regardless of whether the number was out of range in the 
positive or negative direction, and regardless of how far, but I'm by no 
means sure of that.  Thus, the present strtoul() is correct for an input 
string of "-1", but it appears to treat other negative constants as if 
they were first converted to a signed long and then to an unsigned long, 
which I think is incorrect.

-Eric Rudd