PHP multi-dimensional array quickly queries its parent key and parent key value based on the key name

/**
* FILE_NAME : arr.php FILE_PATH : test/
* Quickly query the parent key and parent key value according to the key name in a multi-dimensional array
*
* @copyright Copyright (c) 2006-2010
* @author Levi
* @ package test.arr
* @subpackage
* @version 2011-04-29
* @link bbs.it-home.org
*/
header("Content-Type: text/html; charset=utf-8");
$arr = array
(
'china' = > array
(
'name' => 'China',
'cite' => array
(
'beijing' => array
(
'name' => 'Beijing',
'site ' => array('chaoyang' => 'Chaoyang District', 'xuanwu' => 'Xuanwu District')
),
'shanghai' => array
(
'name' => 'Shanghai ',
'site' => array('jingan' => 'Jing'an District', 'huangpu' => 'Huangpu District')
)
)
)
);
function printA($data)
 {
echo '';</li>
<li>print_r($data);</li>
<li>echo '';
}
function indexKey($data, $parent = NULL)
{
$arr = array() ;
foreach ($data as $key => $value)
{
$arr[$key] = $parent;
if (is_array($value))
{
$arr += indexKey($value, $ key);
}
}
return (Array)$arr;
}
printA(indexKey($arr));
?>

Print the data as follows Array ( [china] => [name] => china [cite] => china [beijing] => cite [site] => beijing [chaoyang] => site [xuanwu] => site [shanghai] => cite [jingan] => site [huangpu] => site ) However, there is a problem with writing the above, that is: if there is a key with the same name, it will be lost, so I wrote such a class Just pass the array to the object, the object provides two interfaces printArr prints index array search queries the parent array key name of the key name IndexKey creates query index query class:

/**
* FILE_NAME : arr.php FILE_PATH : test/
* Quickly query the parent key and parent key value according to the key name in a multi-dimensional array
*
* @copyright Copyright (c) 2006-2010
* @author Levi
* @ package test.arr
* @subpackage
* @version 2011-04-29
* @link bbs.it-home.org
*/
header("Content-Type: text/html; charset=utf-8");
$arr = array
(
'china' => array
(
'name' => 'China',
'cite' => array
(
'beijing' => array
(
'name' => 'Beijing',
' site' => array('chaoyang' => 'Chaoyang District', 'xuanwu' => 'Xuanwu District')
),
'shanghai' => array
(
'name' => ' Shanghai',
'site' => array('jingan' => 'Jing'an District', 'huangpu' => 'Huangpu District')
)
)
)
);
function printA($data)
{
echo '';</li>
<li>print_r($data);</li>
<li>echo '';
}
function printP(IndexKey $obj, $key)
{
$parent = $obj- >search($key);
if ($parent)
{
echo '"'.$key.'" Parent Key is: ';
if (!is_array($parent))
{
echo $parent. "n";
}
else printA($parent);
}
else echo 'NO Parent OR No Search of "'.$key.'"!'." n";
}
class IndexKey
{
private $_arr = array();
public function __construct($data)
{
$this->_createIndex($data);
}
 public function printArr()
{
return (Array)$this->_arr;
}
public function search($key)
{
return isset($this->_arr[$key]) ? $this- >_arr[$key] : NULL;
}
private function _createIndex($data, $parent = NULL)
{
foreach ($data as $key => $value)
{
$this->_checkIndex ($key, $parent);
if (is_array($value))
{
$this->_createIndex($value, $key);
}
}
}
private function _checkIndex($key, $parent )
{
$index = isset($this->_arr[$key]) ? $this->_arr[$key] : NULL;
if ($index)
{
if (is_array($index) )
{
array_push($this->_arr[$key], $parent);
}
else $this->_arr[$key] = array($index, $parent);
}
else $ this->_arr[$key] = $parent;
}
}
$index = (Object)new IndexKey($arr);
printA($index->printArr());
printP($index, 'beijing');
printP($index, 'name');
printP($index, 'china');
?>

In the end, there was only one data output left, so I modified this class Provides three external methods printArr prints index array search queries the parent array key name of the key name parentValue queries the parent key value

/**
* FILE_NAME : arr.php FILE_PATH : test/
* Quickly query the parent key and parent key value according to the key name in a multi-dimensional array
*
* @copyright Copyright (c) 2006-2010
* @author Levi
* @ package test.arr
* @subpackage
* @version 2011-04-29
* @link bbs.it-home.org
*/
header("Content-Type: text/html; charset=utf-8");
$arr = array
(
'china' => array
(
'name' => 'China',
'cite' => array
(
'beijing' => array
(
'name' => 'Beijing',
' site' => array('chaoyang' => 'Chaoyang District', 'xuanwu' => 'Xuanwu District')
),
'shanghai' => array
(
'name' => ' Shanghai',
'site' => array('jingan' => 'Jing'an District', 'huangpu' => 'Huangpu District')
)
)
)
);
function printA($data)
{
echo '';</li>
<li>print_r($data);</li>
<li>echo '';
}
function printP2(IndexArr $obj, $key)
{
$parent = $obj- >search($key);
if (!is_array($parent))
{
if ($parent)
{
echo '"'.$key.'" Parent Key is: '.$parent."< ;br />n";
}
else echo 'NO Parent OR No Search of "'.$key.'"!'."n";;
echo '"'.$key .'" Parent "'.$parent.'" Value is: ';
printA($obj->parentValue($key));
}
else printA($parent);
}
class IndexArr
{
 private $_arr = array();
public function __construct($data)
{
$this->_createIndex($data);
}
public function printArr()
{
return (Array)$this-> _arr;
}
public function search($key)
{
return isset($this->_arr[$key]) ? $this->_arr[$key]['parent'] : NULL;
}
public function parentValue($key)
{
return isset($this->_arr[$key]) ? $this->_arr[$key]['data'] : NULL;
}
private function _createIndex ($data, $parent = NULL)
{
foreach ($data as $key => $value)
{
$this->_checkIndex($key, $parent, $data);
if (is_array( $value))
{
$this->_createIndex($value, $key);
}
}
}
private function _checkIndex($key, $parent, $data)
{
$data = $parent & isset($data[$parent]) ? $data[$parent] : $data;
!isset($this->_arr[$key]) & $this->_arr[$key] = array(' data' => $data, 'parent' => '');
$index = &$this->_arr[$key]['parent'];
if (!empty($index))
 {
if (is_array($index))
{
array_push($index, $parent);
}
else $index = array($index, $parent);
}
else $index = $parent;
}
}
$index2 = (Object)new IndexArr($arr);
printA($index2->printArr());
printP2($index2, 'beijing');
printP2($index2, 'name') ;
printP2($index2, 'china');
?>