3v4l.org

run code in 300+ PHP versions simultaneously
<?php mb_substitute_character(0xfffd); var_dump(bin2hex(mb_convert_encoding("A\xfd\xbf\xbf\xbf\xbf\xbfB", 'UTF-16', 'UTF-8')));
preferences:
31.99 ms | 402 KiB | 5 Q