3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = 3; $b=4; echo "\na ".$a; echo "\nb ".$b; $a ^= $b; echo "\na ".$a; echo "\nb ".$b; $b ^= $a; echo "\na ".$a; echo "\nb ".$b;
Output for 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 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
a 3 b 4 a 7 b 4 a 7 b 3

preferences:
263.59 ms | 403 KiB | 213 Q