#47418 [NoF->Fbk]: number_format misbehaving with some values

ID: 47418 Updated by: pajoye@php.net Reported By: cu19 at gmx dot de -Status: No Feedback +Status: Feedback Bug Type: *Math Functions Operating System: WinXP SP3 PHP Version: 5.3CVS-2009-02-17 (CVS) New Comment: For the garbage problem, that's something else. Can you provide a reproduce script (with data) please? Previous Comments: ------------------------------------------------------------------------ [2010-02-12 11:31:41] tdietsche at comcast dot net this sure IS a bug, scott_mac you need to wake up, if this is the best that php handles floating point then it is worthless. In reading a value of "19" from an excel spreadsheet via odbc, it formats it as "18.:0" which is pure garbage and a bug to me. How can you defend that? I can send my code if you want. ------------------------------------------------------------------------ [2009-02-25 01:00:01] php-bugs at lists dot php dot net No feedback was provided for this bug for over a week, so it is being suspended automatically. If you are able to provide the information that was originally requested, please do so and change the status of the bug back to "Open". ------------------------------------------------------------------------ [2009-02-17 11:20:31] scottmac@php.net scott@skinny [~] $ php -r 'var_dump(number_format(3.9, 2));' string(4) "3.90" Can't reproduce this on Linux. ------------------------------------------------------------------------ [2009-02-17 10:35:08] cu19 at gmx dot de I don't think it's a problem with limited precision but rather about the function itself. I think a float should be able to represent 3 digits without a problem. The hex representation of the float that is to be formatted is 0x40799998, which equals to about 3.8999996. I think number_format should be able to round this to '3.90' instead of displaying it as '3.8:' ------------------------------------------------------------------------ [2009-02-17 10:18:32] scottmac@php.net Floating point values have a limited precision. Hence a value might not have the same string representation after any processing. That also includes writing a floating point value in your script and directly printing it without any mathematical operations. If you would like to know more about "floats" and what IEEE 754 is, read this: http://docs.sun.com/source/806-3568/ncg_goldberg.html Thank you for your interest in PHP. It's the way floating point numbers work in computers, the canned response gives you a link to read about this some more. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/47418 -- Edit this bug report at http://bugs.php.net/?id=47418&edit=1