- array_keys: documentation ( source)
<?php
$str_arr = Array
(
0 => Array
(
'street' => 'Erste Strasse',
'street_id' => 1
),
1 => Array
(
'street' => 'llll',
'street_id' => 2
)
);
#echo $str_arr[array_keys($str_arr)['lalala']];
echo array_keys($str_arr);