Online PHP editor | refs for ueSBB

<?php $arr = [ 'USA' => [ 'Alabama' => [ 'Montgomery', 'Birmingham' ], 'Arizona' => [ 'Phoenix', 'Mesa', 'Gilbert' ] ], 'Germany' => [ 'West Germany' => [ 'Bonn', 'Cologne' ] ] ]; $iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($arr)); $keys = array(); foreach ($iterator as $key => $value) { // Build long key name based on parent keys $key = [$key]; for ($i = $iterator->getDepth() - 1; $i >= 0; $i--) { //$key = $iterator->getSubIterator($i)->key() . '_' . $key; array_unshift($key, $iterator->getSubIterator($i)->key()); } $key[] = $value; $keys[] = $key; } var_export($keys);