3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = [1,2,3]; foreach($a as &$num) {} echo json_encode($a); foreach($a as $num) { echo json_encode($a); } echo implode(',',$a).PHP_EOL; // 1,2,2
Output for 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 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
[1,2,3][1,2,1][1,2,2][1,2,2]1,2,2

preferences:
189.13 ms | 403 KiB | 189 Q