3v4l.org

run code in 300+ PHP versions simultaneously
<?php $x = 0; $a = array(&$x); $b = $a; $x = 2; unset($x); $b[1]++; $b[0]++; echo $a[0], ' ', $b[0]; // 2 3
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Warning: Undefined array key 1 in /in/kjjYt on line 8 2 3
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.31, 7.4.0 - 7.4.33
Notice: Undefined offset: 1 in /in/kjjYt on line 8 2 3
Output for 7.3.32 - 7.3.33
2 3
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.1 - 5.1.6, 5.2.0 - 5.2.17
Notice: Undefined offset: 1 in /in/kjjYt on line 8 2 3
Output for 5.1.0
Fatal error: fatal flex scanner internal error--end of buffer missed in /in/kjjYt on line 10
Process exited with code 255.
preferences:
214.8 ms | 401 KiB | 342 Q