PHP - 查找数组的父键

PHP - Find parent key of array

提问by Jay Are

I'm trying to find a way to return the value of an array's parent key.

我试图找到一种方法来返回数组的父键的值。

For example, from the array below I'd like to find out the parent's key where $array['id'] == "0002". The parent key is obvious because it's defined here (it would be 'products'), but normally it'd be dynamic, hence the problem. The 'id' and value of 'id' is known though.

例如，从下面的数组中，我想找出 $array['id'] == "0002" 的父键。父键很明显，因为它在此处定义（它将是“产品”），但通常它是动态的，因此存在问题。'id' 和 'id' 的值是已知的。

    [0] => Array
        (
            [data] => 
            [id] => 0000
            [name] => Swirl
            [categories] => Array
                (
                    [0] => Array
                        (
                            [id] => 0001
                            [name] => Whirl
                            [products] => Array 
                               (
                                    [0] => Array
                                        (
                                            [id] => 0002
                                            [filename] => 1.jpg
                                         )
                                    [1] => Array
                                        (
                                            [id] => 0003
                                            [filename] => 2.jpg
                                         )
                                )
                         )
                 )
          )

采纳答案by deceze

A little crude recursion, but it should work:

有点粗糙的递归，但它应该工作：

function find_parent($array, $needle, $parent = null) {
    foreach ($array as $key => $value) {
        if (is_array($value)) {
            $pass = $parent;
            if (is_string($key)) {
                $pass = $key;
            }
            $found = find_parent($value, $needle, $pass);
            if ($found !== false) {
                return $found;
            }
        } else if ($key === 'id' && $value === $needle) {
            return $parent;
        }
    }

    return false;
}

$parentkey = find_parent($array, '0002');

回答by Ignacio Vazquez-Abrams

Since you have a tree structure either of a BFSor DFScan do it. Since the structure is variable a recursive solution would work well. Simply return a sentinel when you find the value, then return the key in the caller.

因为你有一个BFS或DFS的树结构都可以做到。由于结构是可变的，递归解决方案会很有效。找到值时只需返回一个哨兵，然后返回调用者中的键。

回答by chla

function array_to_xml($array, $rootElement = null, $xml = null) {

    $_xml = $xml;

    if ($_xml === null) {
        $_xml = new SimpleXMLElement($rootElement !== null ? $rootElement : '<root/>');
    }

    $has_int_key = 0;

    foreach ($array as $k => $v) {
        if (is_array($v)) {
            if(is_int($k)){
                $this->array_to_xml($v, $k, $_xml->addChild($rootElement));
            } 
            else {
                foreach($v as $key=>$value) {
                    if(is_int($key)) $has_int_key = 1;
                }

              if ($has_int_key) {
                  $this->array_to_xml($v, $k, $_xml);
              } else {
                  $this->array_to_xml($v, $k, $_xml->addChild($k));
              }
            }
        } 
        else {
            $_xml->addChild($k, $v);
        }
    }

    return $_xml->asXML();

}