#49322 [Bgs]: Incorrect array assignment
| From: | anshul at designgrill dot com | Date: | Fri, 21 Aug 2009 21:27:13 +0000 |
| Subject: | #49322 [Bgs]: Incorrect array assignment | ||
| References: | 1 | Groups: | php.bugs |
| Request: | Send a blank email to php-bugs+get-141381@lists.php.net to get a copy of this message | ||
ID: 49322
User updated by: anshul at designgrill dot com
Reported By: anshul at designgrill dot com
Status: Bogus
Bug Type: Arrays related
Operating System: All
PHP Version: 5.2.10
New Comment:
Ok.
But it is not obvious from the documentation. A cautionary statement
should be included in there.
Previous Comments:
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[2009-08-21 21:09:20] colder@php.net
Again, those are expected results, when you copy an array, its
elements that are references will be copied as references. It has always
been like that.
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[2009-08-21 17:21:28] anshul at designgrill dot com
The example you gave behaves expectedly and actually denotes the bug is
valid. I would request you to carefully go through the two code snippets
I gave.
Even when you copy a value by reference the array, the copy is not
actually made and instead the refcount is increased of the array. PHP
will defer the actual copy until any one of the array is actually
modified.
Now when you copy the reference to the any array item, and modify using
that reference, a new copy is created and values updated. But if you
keep the reference of the item in a variable before array copying,
modifying this variable will not force PHP to create the actual copy of
the array.
Incorrect behavior at the best.
------------------------------------------------------------------------
[2009-08-21 17:08:22] colder@php.net
Yes, the array itself is copied by value, but not the array content, as
you discovered.
$a = array();
$b = $a;
$b[] = 2; var_dump(count($a)); // int(0)
------------------------------------------------------------------------
[2009-08-21 17:00:12] anshul at designgrill dot com
Following will give a different result. Just because reference is
copying after assignment.
PHP manual says the assignment operation copies by value for arrays.
<?php
$arr1 = array(1, 2);
$arr2 = $arr1;
$var = &$arr1[0];
$var = 10;
print_r($arr1);
print_r($arr2);
?>
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[2009-08-21 16:54:32] colder@php.net
Sorry, but your problem does not imply a bug in PHP itself. For a
list of more appropriate places to ask for help using PHP, please
visit http://www.php.net/support.php as this bug system
is not the
appropriate forum for asking support questions. Due to the volume
of reports we can not explain in detail here why your report is not
a bug. The support channels will be able to provide an explanation
for you.
Thank you for your interest in PHP.
That's expected, arrays have always worked like that.
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the rest of the comments, please view the bug report online at
http://bugs.php.net/49322
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