Search for a key in an array, recursively

Maybe it's overkill, but it's funny to use RecursiveIterators :)

UPDATE: Maybe it was overkill with old versions of PHP, but with >=5.6 (specially with 7.0) I would totally use this without doubt.

function recursiveFind(array $haystack, $needle)
{
    $iterator  = new RecursiveArrayIterator($haystack);
    $recursive = new RecursiveIteratorIterator(
        $iterator,
        RecursiveIteratorIterator::SELF_FIRST
    );
    foreach ($recursive as $key => $value) {
        if ($key === $needle) {
            return $value;
        }
    }
}

UPDATE: Also, as of PHP 5.6, with generators you can easily iterate over all elements which pass the filter, not only the first one:

function recursiveFind(array $haystack, $needle)
{
    $iterator  = new RecursiveArrayIterator($haystack);
    $recursive = new RecursiveIteratorIterator(
        $iterator,
        RecursiveIteratorIterator::SELF_FIRST
    );
    foreach ($recursive as $key => $value) {
        if ($key === $needle) {
            yield $value;
        }
    }
}

// Usage
foreach (recursiveFind($haystack, $needle) as $value) {
    // Use `$value` here
}

function array_search_key( $needle_key, $array ) {
  foreach($array AS $key=>$value){
    if($key == $needle_key) return $value;
    if(is_array($value)){
      if( ($result = array_search_key($needle_key,$value)) !== false)
        return $result;
    }
  }
  return false;
} 

this will work !

you need to stop the recursive deep search, by return false and then check it in the function.

you can find more examples of functions (like using RecursiveArrayIterator and more) in this link : http://php.net/manual/en/function.array-search.php