Re: Curious int/float/division/math 'gotcha' in py (discussion)

On Tue, Jun 28, 2011 at 2:37 PM, Tom Evans <tevans.uk@googlemail.com> wrote:

On Tue, Jun 28, 2011 at 2:23 PM, Cal Leeming [Simplicity Media Ltd]
<cal.leeming@simplicitymedialtd.co.uk> wrote:

> 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
>

Damn, this was the bit I meant to comment upon - hard and fast rules
are dangerous. Integral types are distinctly different to floating
point types, and you should be aware of which one you are using and
why. You definitely should not be using floats when you require
integral mathematics, or reliable accounting since 1.0 is only an
approximation to 1.

Yeah I have come up against horrible problems before when forcibly re-casting all int's to float's.. (especially when it's in the monetary sense). I had assumed that it would be a on a "per case" basis, but just wanted to make sure.

 

Cheers

Tom


>>> 1.0 * 10000000000000000000000000000
9.9999999999999996e+27

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