From: Mark Probert <probertm@...>
Date: 2002-12-11T03:46:11+09:00
Subject: Re: Proper Type for Dollar Amount

At 03:14 AM 12/11/2002 +0900, Bill T. wrote:
>Jim Weirich <jweirich@one.net> wrote:
> >  Yes, they were using floating point to represent dollar
> > amounts.  Never a good idea.
>
>Well, you can search comp.lang.c about a thread on what type to use
>(int/long/double/etc.) to represent dollar amounts (including the
>cents).  I don't think there is a clear answer that representing dollar
>amounts with floating point is a bad idea.  It depends on what kinds of
>operations you are going to do, which in this case is a division.

My own experience (based on developing real-time trading systems for
some merchant banks), is that the best solution is to use scaled
integers, to 100th of a cent.  So, $154.34 --> 1543400.  You then
get very fast operations (they are all integer operations) and, in
general, well with +- 4 billion.  Ruby, with BigInt makes it trivial.

Regards,
-mark.