The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My work

  • My badges

  • Twitter Updates

  • My Flickr Stream

    20140508-Delphi-2007--Project-Options--Cannot-Edit-Application-Title-HelpFile-Icon-Theming

    20140430-Fiddler-Filter-Actions-Button-Run-Filterset-now

    20140424-Windows-7-free-disk-space

    More Photos
  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 1,296 other followers

Archive for March 8th, 2011

Why is the result of RoundTo(87.285, -2) => 87.28 – Stack Overflow

Posted by Jeroen Pluimers on 2011/03/08

Programmers on all sorts of platforms get this wrong all the time (I admit having done this in bad ways myself too).

In short: Don’t expect floating point values in a computer to be represented as decimals.

Rob Kennedy wrote a very nice answer on this:

The exact value 87.285 is not representable as a floating-point value in Delphi. A page on my Web site shows what that value really is, as Extended, Double, and Single:

87.285 = + 87.28500 00000 00000 00333 06690 73875 46962 12708 95004 27246 09375

87.285 = + 87.28499 99999 99996 58939 48683 51519 10781 86035 15625

87.285 = + 87.28500 36621 09375

And David Heffernan points to the best link you can get on this topic:

The classic reference on floating point is What Every Computer Scientist Should Know About Floating-Point Arithmetic.

For currency based calculations, if indeed this is, you should use a base 10 number type rather than base 2 floating point. In Delphi that means `Currency`.

–jeroen

via delphi – Why is the result of RoundTo(87.285, -2) => 87.28 – Stack Overflow.

Posted in .NET, C#, Delphi, Development, Software Development | 14 Comments »

If you use MonoTouch for iOS, be sure to update the iOS SDK (it doens’t auto update)

Posted by Jeroen Pluimers on 2011/03/08

If you don’t update the Apple iOS SDK (which doesn’t auto update), then the Apple Store will reject your MonoTouch apps.

A big thank you to Peter van Ooijen for figuring this out

–jeroen

via: The appstore, iOs versions and Monotouch (4.0 won’t do) | Visual Studio Feeds.

Posted in .NET, Development, MonoTouch, Software Development | Leave a Comment »

 
Follow

Get every new post delivered to your Inbox.

Join 1,296 other followers

%d bloggers like this: