3v4l.org

run code in 300+ PHP versions simultaneously
<?php for ($i = 0; $i < 4; ++$i) { for ($s = '', $j = 0; $j < 4; ++$j) { $s .= ($i + $j) % 4 + 1; echo $s . "\n"; } }
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
1 12 123 1234 2 23 234 2341 3 34 341 3412 4 41 412 4123
preferences:
123.65 ms | 402 KiB | 121 Q