Yeah I'm aware of this now, but it was more of a "oh, didn't ever notice this before" rather than a "why is this happening" thread :)
I was expecting that dividing two ints would return a float, but it doesn't. It does make sense, just a bit of a gotcha, you know? Cal On Tue, Jun 28, 2011 at 2:31 PM, Tom Evans <tevans...@googlemail.com> wrote: > On Tue, Jun 28, 2011 at 2:23 PM, Cal Leeming [Simplicity Media Ltd] > <cal.leem...@simplicitymedialtd.co.uk> wrote: > > So, today I was confused why on earth dividing two ints (which leaves a > > remainder), didn't return back an int. > > In the end, I re-casted the ints as floats, performed the division, and > this > > worked fine. > > Looked through the docs, and found this: > > http://docs.python.org/library/stdtypes.html > > "For (plain or long) integer division, the result is an integer. The > result > > is always rounded towards minus infinity: 1/2 is 0, (-1)/2 is -1, 1/(-2) > is > > -1, and (-1)/(-2) is 0. Note that the result is a long integer if either > > operand is a long integer, regardless of the numeric value." > > Has anyone else come up against this gotcha before? I'm wondering if it's > > better practise to always cast a number as a float/decimal, rather than > an > > int. > > Any thoughts guys? > > Cal > > Bit OT, but I'll bite (doesn't really relate to Django). Dividing two > ints ALWAYS returns an int. Calling math.ceil() ALWAYS returns a > float. I think you were expecting that python would automagically > store the remainder somewhere so that math.ceil() has something to > operate on. It doesn't do that! > > If you wish to do rounding, convert either operand to a float. The > 'Note that the result is a long integer if either operand is a long > integer' is referring to dividing two integral types - if either is a > long, the result will be a long. It doesn't apply if either operand is > a float, eg if you divide a float by a long, the result is a float, > not a long. > > Cheers > > Tom > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To post to this group, send email to django-users@googlegroups.com. > To unsubscribe from this group, send email to > django-users+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/django-users?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
