Bug #64194 [Ver]: Null variable doesn't give error when trying to use as array
Edit report at https://bugs.php.net/bug.php?id=64194&edit=1
ID: 64194
Updated by: cmb@php.net
Reported by: marius at kitara dot nl
Summary: Null variable doesn't give error when trying to use
as array
Status: Verified
Type: Bug
Package: Arrays related
Operating System: FreeBSD 9.1
PHP Version: 5.4.11
Block user comment: N
Private report: N
New Comment:
Related to bug #65484.
Previous Comments:
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[2013-02-18 13:02:01] nikic@php.net
I would tentatively classify this as a bug. The fact that NULL can be cast to an array by setting a
key (without notice) is intentional, but accessing an undefined key on NULL should throw a notice.
Same applies to other scalar like ints/doubles/...
This is a behavioral difference between zend_fetch_dimension_address and
zend_fetch_dimension_address_read. In one case an array will be created and dispatched to
fetch_from_array (http://lxr.php.net/xref/PHP_TRUNK/Zend/zend_execute.c#1119), in the other case it
just directly returns NULL (http://lxr.php.net/xref/PHP_TRUNK/Zend/zend_execute.c#1265).
This issue also creates a behavioral difference between BP_VAR_R fetches and BP_VAR_RW. E.g.
++$data['wok'] in the above example *will* throw a notice, even though it should be the
same as doing $data['wok'] = $data['wok'] + 1 (which does not throw a notice).
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[2013-02-18 12:53:19] kevin dot swinton at gmail dot com
Without diving into the internals at this point:
$data is initially declared as a variable of type NULL.
In the first echo statement, the attempt to reference an index of 'wok' in $data is
effectively ignored: the variable is not an ARRAY to begin with.
$data is then cast into a variable of type ARRAY ("$data['test'] =
'test';")
In the second echo statement, $data is an array, with an index, which PHP can enumerate against and
ultimately determine that index 'wok' is not present.
Hence the first echo results in a NULL output, whilst the second results in PHP issuing an E_NOTICE.
I'd submit this issue is not related to the PHP core.
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[2013-02-12 10:50:42] marius at kitara dot nl
Description:
------------
When you define a string as null value you won't get any undefined errors. As soon you define a
value in that same string you will see undefined errors.
Test script:
---------------
<?php
ini_set('display_errors', 1);
error_reporting(E_ALL | E_STRICT);
$data = null;
echo $data['wok']; // Remains silent
$data['test'] = 'test';
echo $data['wok']; // Gives an undefined error
Expected result:
----------------
Both echo lines should give an undefined error.
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