3v4l.org

run code in 300+ PHP versions simultaneously
<?php class t { public static $foo; static function changeFoo($value){ self::$foo = $value; } } t::changeFoo("One"); print(t::$foo); t::changeFoo("Two"); print(t::$foo);
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.29 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
OneTwo

preferences:
183.6 ms | 404 KiB | 164 Q