[Python-ideas] Negative hexes

[Antoine Pitrou]

On Sat, 3 Dec 2011 09:05:02 -0800
Guido van Rossum <guido at python.org> wrote:
> On Sat, Dec 3, 2011 at 8:45 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> 
> > On Sat, 3 Dec 2011 14:31:51 +1000
> > Nick Coghlan <ncoghlan at gmail.com> wrote:
> > >
> > > If you really want that (Why would you?) and so long as the numbers
> > > aren't negative:
> > >
> > >     "0B{:b}".format(number)
> > >     "0O{:o}".format(number)
> > >
> > > The only reason 'X' is provided for hexadecimal formatting is to
> > > capitalize the letters that appear within the number itself.
> >
> > By the way, any reason why hex output represents negative number with a
> > negative sign (instead of the more usual 2s-complement representation)?
> >
> > It's not too difficult to normalize by hand (e.g. add 2**32 if you know
> > the number is a 32-bit one) but it always irks me that Python doesn't
> > do it by default. I cannot think of a situation where the "sign" is
> > relevant when printing a hex number: hex is about the raw binary
> > representation of the number.
> >
> 
> This is because Python's integers are not limited to 32 bits or 64 bits. If
> you read PEP 237, you'll see that this was one of the hardest differences
> between ints and longs to be resolved. You'd have to include an infinite
> number of leading 'F' characters to format a negative long this way...

That's a fair point :)

Regards

Antoine.