3v4l.org

run code in 300+ PHP versions simultaneously
<?php function arrayFlat($arr){ $out = ''; foreach($arr as $key => $value){ if(!is_array($value)){ $out .= $value.','; }else{ $out .= $key.','; $out .= arrayFlat($value); } } return trim($out,','); } $aNonFlat = array( 1, 2, array( 3, 4, 5, array( 6, 7 ), 8, 9, ), 10, 11 ); $result = explode(',',arrayFlat($aNonFlat)); echo '<pre>'; print_r($result); echo '</pre>';

preferences:
60.83 ms | 402 KiB | 5 Q