3v4l.org

run code in 300+ PHP versions simultaneously
<?php $array_x = array(); $array_x['a'] = array(1,2,3,4); $array_x['b'] = array(2,3,4,5); foreach ($array_x as $k => &$v) { foreach ($v as $x) { $x = $x * 2; } } var_dump($array_x);

preferences:
37.92 ms | 402 KiB | 5 Q