Sorry for my english...

I wrote a function to get keys of arrays recursivelly...

<?php
    function recursive_keys($input, $search_value = null){

        $output = ($search_value !== null ? array_keys($input, $search_value) : array_keys($input)) ;
        foreach($input as $sub){
            if(is_array($sub)){
                $output = ($search_value !== null ? array_merge($output, recursive_keys($sub, $search_value)) : array_merge($output, recursive_keys($sub))) ;
            }
        }
        return $output ;
    }
?>

I hope it will be usefull

Regards