3v4l.org

run code in 300+ PHP versions simultaneously
<?php echo mb_strlen("\xF4\x8F\xBF\xBF\xF4\x8F\xBF\xBF\xF4\x8F\xBF\xBF", 'UTF-8');

preferences:
37.18 ms | 402 KiB | 5 Q