Re: PHP 4.0 Bug #9411 Updated: Arithmetic error

Hi, can't we make this a FAQ? (if I get no response, it's in the FAQ in 60 mins :) Derick On 22 Feb 2001 lyric@php.net wrote: > ID: 9411 > Updated by: lyric > Reported By: robburne@hotmail.com > Old-Status: Closed > Status: Bogus > Old-Bug Type: *Regular Expressions > Bug Type: Math related > Assigned To: > Comments: > > This is nothing to do with PHP, its just part of the way computers store floating-point > numbers. It stores an aproximation of 0.32, as close as it can get, but when you start multiplying > it, the little difference between 0.32 and what it stored starts to get magnified. > > BTW, 5.5511151231258E-17 is 0.000000000000000055511151231258 which is *really* closed to 0. > > If you want to output formatted numbers, you should either round it, or use printf() > http://www.php.net/manual/en/function.printf.php > > > Previous Comments: > --------------------------------------------------------------------------- > > [2001-02-22 16:05:47] derick@php.net > This is normal floating point math behavior > > --------------------------------------------------------------------------- > > [2001-02-22 15:45:55] robburne@hotmail.com > Hi I am not sure if I have found a bug - what do you think.......? > > Consider this: > > $var1 = -0.32 + (0.1*3.2) > > This should give var1 the value 0, instead it gives > > 5.5511151231258E-17 > > Interestingly if you increase -0.33 and 3.3 respectively it gives the correct answer. Werid! > > Rob Burne > > robburne@hotmail.com > > > --------------------------------------------------------------------------- > > > > ATTENTION! Do NOT reply to this email! > To reply, use the web interface found at > http://bugs.php.net/?id=9411&edit=2 > > > -- > PHP Development Mailing List <http://www.php.net/> > To unsubscribe, e-mail: php-dev-unsubscribe@lists.php.net > For additional commands, e-mail: php-dev-help@lists.php.net > To contact the list administrators, e-mail: php-list-admin@lists.php.net > Derick Rethans --------------------------------------------------------------------- PHP: Scripting the Web - www.php.net - derick@php.net SRM: Site Resource Manager - www.vl-srm.net --------------------------------------------------------------------- JDI Media Solutions - www.jdimedia.nl - d.rethans@jdimedia.nl Boulevard Heuvelink 102 - 6828 KT Arnhem - The Netherlands ---------------------------------------------------------------------