php.net |  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login

go to bug id or search bugs for

Bug #43241 Float Precision/Representation and Modulo
Submitted: 2007-11-11 02:44 UTC Modified: 2007-11-11 15:08 UTC
From: quake5 at gmx dot de Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 5.2.5 OS: MacOS
Private report: No CVE-ID: None
View Developer Edit
Welcome back! If you're the original bug submitter, here's where you can edit the bug or add additional notes.
If you forgot your password, you can retrieve your password here.
Password:
Status:
Package:
Bug Type:
Summary:
From: quake5 at gmx dot de
New email:
PHP Version: OS:

 

 [2007-11-11 02:44 UTC] quake5 at gmx dot de 
Description:
------------
Float Precision/Representation and Modulo

Reproduce code:
---------------
<?php

var_dump(73.82 * 100 % 2);

?>

Expected result:
----------------
int(0)

Actual result:
--------------
int(1)

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2007-11-11 10:49 UTC] felipe@php.net 
This is documented. 
See "Integer overflow" ( http://br.php.net/integer )

felipe@pena:~$ php -r 'var_dump(73.82 * 100);'
float(7382)
felipe@pena:~$ php -r 'var_dump(73.82 * 100 % 2);'
int(1)
felipe@pena:~$ php -r 'var_dump(round(73.82 * 100) % 2);'
int(0)
 [2007-11-11 15:08 UTC] derick@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.

.
 
PHP Copyright © 2001-2025 The PHP Group
All rights reserved. 		Last updated: Tue Dec 02 00:00:01 2025 UTC