On Fri, Oct 10, 2008 at 9:33 PM, Steven Hamilton <[EMAIL PROTECTED]> wrote: > I'm still unsure why I'm getting 4 decimal places as I know for fact that > the data is 2 decimal places. However, it seems my approach is wrong. I'll > convert to int's and NSDecimalNumbers instead and remove all floats.
The problem is that you don't really know that the data has two decimal places. As Mike Ash pointed out, IEEE floating point can rarely exactly specify a number that only has two decimal places. So though you might write a literal "1.23" in your code, the compiler converts it to a number like "1.2300000000000001". In fact, go ahead and launch Terminal.app and run `python`. Type 1.23, and the interpreter will give you back "1.23". Then type "1.23 * 10", and watch as the interpreter gives you "12.300000000000001". This article, "7 Top Tips for Coding with Currency", just made it to progamming.reddit.com about four days ago. It gives a very nice summary of the issues involved when dealing with currency -- not surprisingly, the first one is "work with integer minor units, and never ever ever use floating point numbers". --Kyle Sluder _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
