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

go to bug id or search bugs for

Bug #69039 (int)
Submitted: 2015-02-12 09:26 UTC Modified: 2015-02-12 11:39 UTC
Votes:1
Avg. Score:3.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:0 (0.0%)
Same OS:1 (100.0%)
From: marc at webetsolutions dot com Assigned:
Status: Not a bug Package: *General Issues
PHP Version: Irrelevant OS: Linux
Private report: No CVE-ID: None
View Developer Edit
 [2015-02-12 09:26 UTC] marc at webetsolutions dot com 
Description:
------------
Just a litle question

if i calculate 

echo 264.40 * 100;
The result is : 26440

if i calculate 
echo (int)(264.40 * 100);
The result is 26439

The problem seem to be for 255 to 327

Why ?

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2015-02-12 11:39 UTC] nikic@php.net
-Status: Open +Status: Not a bug
 [2015-02-12 11:39 UTC] nikic@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://www.floating-point-gui.de/

Thank you for your interest in PHP.
 [2015-02-12 11:41 UTC] nikic@php.net 
(int) casts are truncating (which means "round down" in this case). Due to limited floating point precision 264.40 * 100 is in reality something like 26439.999999999, which is then rounded down to 26439. You may try setting the "precision" ini setting to a higher value in order to see this.
 
PHP Copyright © 2001-2024 The PHP Group
All rights reserved. 		Last updated: Sun Dec 22 06:01:30 2024 UTC