3v4l.org

run code in 300+ PHP versions simultaneously
<?php error_reporting(0); $a = "abcdefffefa"; for($i = 0; $i < 12; $i++) $a = $a . $a; $b = "afe"; print(str_replace(array_unique(str_split($b)), "", $a));

preferences:
38.95 ms | 402 KiB | 5 Q