[Python-Dev] Floor division

Guido van Rossum guido at python.org
Fri Jan 26 16:01:44 CET 2007


Nick, I didn't write that; Tim did. If you're going to enter into a
pedantic discussion, at least get your attributions right,

On 1/26/07, Nick Maclaren <nmm1 at cus.cam.ac.uk> wrote:
> "Guido van Rossum" <guido at python.org> wrote:
> >
> > "(int)float_or_double" truncates in C (even in K&R C) /provided that/
> > the true result is representable as an int.  Else behavior is
> > undefined (may return -1, may cause a HW fault, ...).
>
> Actually, I have used Cs that didn't, but haven't seen any in over
> 10 years.  C90 is unclear about its intent, but C99 is specific that
> truncation is towards zero.  This is safe, at least for now.
>
> > So Python uses C's modf() for float->int now, which is always defined
> > for finite floats, and also truncates.
>
> Yes.  And that is clearly documented and not currently likely to
> change, as far as I know.
>
>
> Regards,
> Nick Maclaren,
> University of Cambridge Computing Service,
> New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
> Email:  nmm1 at cam.ac.uk
> Tel.:  +44 1223 334761    Fax:  +44 1223 334679
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-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)


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