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

go to bug id or search bugs for

Bug #49112 Problem with float numbers - only in one case
Submitted: 2009-07-30 16:56 UTC Modified: 2009-07-30 17:12 UTC
From: marek at 3v dot ie Assigned:
Status: Not a bug Package: Math related
PHP Version: 5.2.10 OS: Fedora 9
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: marek at 3v dot ie
New email:
PHP Version: OS:

 

 [2009-07-30 16:56 UTC] marek at 3v dot ie 
Description:
------------
When I try to substract specific float numbers I receive a wrong result


Reproduce code:
---------------
echo (35.19 - 31.69 - 3.50);
echo (36.19 - 31.69 - 2.50);

Expected result:
----------------
0

Actual result:
--------------
-3.5527136788005E-15

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2009-07-30 17:12 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 May 13 13:01:27 2025 UTC