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

go to bug id or search bugs for

Bug #71009 A reference references multiple variables after clone.
Submitted: 2015-12-01 14:24 UTC Modified: 2015-12-01 15:57 UTC
From: remyfox at hotmail dot com Assigned:
Status: Not a bug Package: Class/Object related
PHP Version: 5.6.16 OS: Windows
Private report: No CVE-ID: None
View Developer Edit
Welcome! If you don't have a Git account, you can't do anything here.
If you reported this bug, you can edit this bug over here.
(description)
Block user comment
Status: Assign to:
Package:
Bug Type:
Summary:
From: remyfox at hotmail dot com
New email:
PHP Version: OS:

 

 [2015-12-01 14:24 UTC] remyfox at hotmail dot com 
Description:
------------
The values that are printed are both 11 and 12. I doubt this is correct behaviour.

Test script:
---------------
class A {
    public $z = 10;
}

$a1 = new A();

$z = &$a1->z;

$a2 = clone $a1;

$a1->z = 11;

var_dump($z);

$a2->z = 12;

var_dump($z);

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2015-12-01 15:57 UTC] leigh@php.net
-Status: Open +Status: Not a bug
 [2015-12-01 15:57 UTC] leigh@php.net 
Hi,

This is intentional behaviour and is documented in the manual.

http://php.net/manual/en/language.oop5.cloning.php

"When an object is cloned, PHP 5 will perform a shallow copy of all of the object's properties. Any properties that are references to other variables will remain references."

`$z = &$a1->z;` makes both sides of the assignment references to the same value, and since $a1->z is now a reference it is cloned as a reference.
 
PHP Copyright © 2001-2025 The PHP Group
All rights reserved. 		Last updated: Fri Oct 24 08:00:01 2025 UTC