3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = array(1,2,3); $b = &$a; foreach($a as $key => $v) { echo "$v\n"; if ($key === 0) unset($a[1]); }
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 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
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28
1 3

preferences:
154.64 ms | 401 KiB | 179 Q