SPUG: Working with currency
bill at celestial.com
Thu Apr 2 23:04:17 PDT 2009
On Thu, Apr 02, 2009, Michael R. Wolf wrote:
> On Apr 2, 2009, at 8:46 PM, Yitzchak Scott-Thoennes wrote:
>> The only pre-existing solution that's going to work consistently is:
>> Store and manipulate in pennies; only use dollars on user input and
>> No modules required. :)
> A module-less solution was my first choice. It's elegant (for the
> "small and simple" definition of elegant).
> After an hour of digging, I can't find indications (much less an answer)
> on when it's necessary to 'use bigint'. In other words, what is the
> moral equivalent of MAXINT, or at least a close approximation
> (disregarding whatever legal fine-print exists) for a back of the
> envelope proof-of-concept design?
That depends on the underlying hardware and the integer length.
Normal longs will handle things most small-to-medium businesses
normally deal with (until Hyperinflation hits which is coming RSN
to a neighborhood near you). Dollar amounts are stored
internally as cents. Addition and subtraction is a no-brainer,
but multiplication and division is a bit messier as one needs to
normalize to cents with appropriate rounding rules.
It would be in interesting exercise in OO programming and
overriding operators to create a class that would handle fixed
point decimal numbers properly. I did something like this
several years ago in perl, but generally find dealing with
bigints to be pretty ugly.
INTERNET: bill at celestial.com Bill Campbell; Celestial Software LLC
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