note 81835 added to function.array-walk-recursive

This function has a serious bug, which is still not fixed as of the PHP 5.2.5 release. After you call it, it can accidentally modify your original array. Save yourself hours of frustration by reading on. The bug is here: http://bugs.php.net/bug.php?id=42850, and it looks like it will be fixed for 5.3. If the array that you walk contains other array elements, they will be turned into references. This will happen even if the callback function doesn't take its first argument by reference, and doesn't do anything to the values. For example, try this: <?php $data = array ('key1' => 'val1', 'key2' => array('key3' => 'val3')); function foo($item, $key){} var_dump($data); ?> The original array has no references. Now try this: <?php array_walk_recursive($data,'foo'); var_dump($data); ?> Now key2 is a reference, not just an array. So if you do this: <?php function test($item){$item['key2'] = array();} test($data); var_dump($data); ?> you will see that test modifies $data, even though it shouldn't. One workaround is to immediately make a deep copy of the array after calling array_walk_recursive, like this: <?php function array_duplicate($input) { if (!is_array($input)) return $input; $output = array(); foreach ($input as $key => $value) { $output[$key] = array_duplicate($value); } return $output; } array_walk_recursive($data,'foo'); $data = array_duplicate($data); var_dump($data); ?> After doing that, the references are gone. ---- Server IP: 217.160.72.57 Probable Submitter: 69.181.0.49 ---- Manual Page -- http://www.php.net/manual/en/function.array-walk-recursive.php Edit -- https://master.php.net/note/edit/81835 Del: integrated -- https://master.php.net/note/delete/81835/integrated Del: useless -- https://master.php.net/note/delete/81835/useless Del: bad code -- https://master.php.net/note/delete/81835/bad+code Del: spam -- https://master.php.net/note/delete/81835/spam Del: non-english -- https://master.php.net/note/delete/81835/non-english Del: in docs -- https://master.php.net/note/delete/81835/in+docs Del: other reasons-- https://master.php.net/note/delete/81835 Reject -- https://master.php.net/note/reject/81835 Search -- https://master.php.net/manage/user-notes.php