#36008 [Opn->Fbk]: Mishandled type 'double' causes incorrect round() & number_format() output

ID: 36008 Updated by: sniper@php.net Reported By: adi at rogers dot com -Status: Open +Status: Feedback Bug Type: Math related Operating System: win32 only PHP Version: 5.1.2 New Comment: What EXACTLY is the output when you set precision to 32? Previous Comments: ------------------------------------------------------------------------ [2006-01-14 15:55:07] adi at rogers dot com I just confirmed this issue to still exist on the following systems: Windows XP Pro SP2 [IIS 5.1 ISAPI] (PHP 5.1.2 / php.ini precision: 12) Windows XP Pro SP2 [IIS 5.1 CGI] (PHP 5.1.0RC1 / php.ini precision: 12) Windows Server 2003 Enterprise x64 Edition SP1 [IIS 6.0 CGI] (PHP 5.1.2 / php.ini precision: 12) PHP was installed on all three systems manually (not using the installer). Hope that helps in isolating this issue. ------------------------------------------------------------------------ [2006-01-14 11:16:57] sniper@php.net Output on my machine using default precision 12: Wrong: 14.38 Wrong: 14.38 'Magically' correct: 14.38 'Magically' correct: 14.38 Converted to string and is now correct: 14.38 Converted to string and is now correct: 14.38 And it works exactly like it's supposed to. round() rounds up to 2 decimals. Same goes for number_format(). 14.375 == 14.38 but 14.374 == 14.37 There is no bug here, and please, don't bother reopening this yet again. ------------------------------------------------------------------------ [2006-01-14 05:15:52] adi at rogers dot com Description: ------------ Very lame/unreliable ;) Both round() and number_format() succumb to this problem. They cannot handle float or double variables properly even though those variable types are "flawed / limited" as apparently described numerous times on here by PHP personnel. Well my code below appears to showcase the bug which will hopefully not be shot off as "bogus" like many times before as reported in the past by various people. I found a work-around which I will now be using. Convert your value to a string variable before passing it to the round() or number_format() function. Reproduce code: --------------- $num=12.5*1.15; // Produces 14.375 as type: double. $num_same_thing=14.375; // Produces 14.375 as type: double. echo "Wrong: ".round($num, 2)."\r\n"; echo "Wrong: ".number_format($num, 2)."\r\n"; echo "'Magically' correct: ".round($num_same_thing, 2)."\r\n"; echo "'Magically' correct: ".number_format($num_same_thing, 2)."\r\n"; // The above two variables are the same value and same type, yet are rounded differently. settype($num, "string"); // Now that $num is a string, we get the right result. echo "Converted to string and is now correct: ".round($num, 2)."\r\n"; echo "Converted to string and is now correct: ".number_format($num, 2)."\r\n"; Expected result: ---------------- The functions should have outputted 14.38 no matter how the variables of type 'double' were assigned the value 14.375. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=36008&edit=1