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."x"; $item=$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 - 5.5.38, 5.6.0 - 5.6.38, 7.0.0 - 7.0.33, 7.1.0 - 7.1.25, 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_0xxx [1] => 1_1xxx [2] => 1_2xxx [3] => 1_3xxx [4] => 2_4xx [5] => 2_5xx [6] => 2_6xx [7] => 2_7xx ) 1_0xxx 1_1xxx 1_2xxx 1_3xxx 2_4xx 2_5xx 2_6xx 2_6xx Array ( [0] => 1_0xxx [1] => 1_1xxx [2] => 1_2xxx [3] => 1_3xxx [4] => 2_4xx [5] => 2_5xx [6] => 2_6xx [7] => 2_6xx )
preferences:
296.35 ms | 406 KiB | 424 Q