3v4l.org

run code in 300+ PHP versions simultaneously
<?php $a = '\abc'; var_dump(preg_match('/^\\\\a/', $a));
Output for 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.29, 8.0.0 - 8.0.19, 8.1.0 - 8.1.6
int(1)

preferences:
46.62 ms | 409 KiB | 5 Q