3v4l.org

run code in 300+ PHP versions simultaneously
<?php $items=array(); for ($j=1;$j<=2;$j++) { for ($i=0;$i<4*$j;$i++) { $item=&$items[$i]; if (!isset($item)) $item=$j."_".$i; $item=$item.="x"; } } print_r($items); foreach ($items as $item) echo $item."\n"; print_r($items);
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.35, 5.6.0 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Array ( [0] => 1_0xx [1] => 1_1xx [2] => 1_2xx [3] => 1_3xx [4] => 2_4x [5] => 2_5x [6] => 2_6x [7] => 2_7x ) 1_0xx 1_1xx 1_2xx 1_3xx 2_4x 2_5x 2_6x 2_6x Array ( [0] => 1_0xx [1] => 1_1xx [2] => 1_2xx [3] => 1_3xx [4] => 2_4x [5] => 2_5x [6] => 2_6x [7] => 2_6x )
preferences:
265.77 ms | 406 KiB | 373 Q