3v4l.org

run code in 300+ PHP versions simultaneously
<?php error_reporting(E_ALL); function out(&$x) { $x = 1; } out($a); $b = NULL; out($b); out($c = NULL); echo "[$a,$b,$c]";
Output for 8.3.0 - 8.3.6
Fatal error: Uncaught Error: out(): Argument #1 ($x) could not be passed by reference in /in/bndPo:7 Stack trace: #0 {main} thrown in /in/bndPo on line 7
Process exited with code 255.
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18
Fatal error: Uncaught Error: out(): Argument #1 ($x) cannot be passed by reference in /in/bndPo:7 Stack trace: #0 {main} thrown in /in/bndPo on line 7
Process exited with code 255.
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33
Notice: Only variables should be passed by reference in /in/bndPo on line 7 [1,1,]
Output for 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28
Strict Standards: Only variables should be passed by reference in /in/bndPo on line 7 [1,1,]
Output for 5.1.2 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29
[1,1,]
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.1
[1,1,1]

preferences:
212.5 ms | 402 KiB | 315 Q