3v4l.org

run code in 300+ PHP versions simultaneously
<?php function foo($arg){ $var = 'check:'.$arg; echo $var; } preg_replace('/a/', foo("$1"), 'a');
Output for 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
check:$1 Deprecated: preg_replace(): Passing null to parameter #2 ($replacement) of type array|string is deprecated in /in/Xj8kF on line 6
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.12 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30
check:$1
preferences:
226.94 ms | 405 KiB | 313 Q