3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = ["úù" => "u"]; echo preg_match('/['. $k . ']/', $v, 'olocú');
Output for 8.3.0 - 8.3.6
Warning: Undefined variable $k in /in/1LWGZ on line 5 Warning: Undefined variable $v in /in/1LWGZ on line 5 Fatal error: Uncaught Error: preg_match(): Argument #3 ($matches) could not be passed by reference in /in/1LWGZ:5 Stack trace: #0 {main} thrown in /in/1LWGZ on line 5
Process exited with code 255.
Output for 8.1.23 - 8.1.28, 8.2.10 - 8.2.18
Warning: Undefined variable $k in /in/1LWGZ on line 5 Warning: Undefined variable $v in /in/1LWGZ on line 5 Fatal error: Uncaught Error: preg_match(): Argument #3 ($matches) cannot be passed by reference in /in/1LWGZ:5 Stack trace: #0 {main} thrown in /in/1LWGZ on line 5
Process exited with code 255.
Output for 5.4.0 - 5.4.28
Fatal error: Only variables can be passed by reference in /in/1LWGZ on line 5
Process exited with code 255.
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.28
Parse error: syntax error, unexpected '[' in /in/1LWGZ on line 3
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected '[' in /in/1LWGZ on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/1LWGZ on line 3
Process exited with code 255.

preferences:
131.43 ms | 401 KiB | 138 Q