Encode a high code point (> U+FFFF) to HTML entities

Question

I have an input string (URL-encoded):

%F0%9F%98%8E

which decoded is the emoji \"

Answer 1

<?php

function mb_ord($char, $encoding = 'UTF-8') {
    if ($encoding === 'UCS-4BE') {
        list(, $ord) = (strlen($char) === 4) ? @unpack('N', $char) : @unpack('n', $char);
        return $ord;
    } else {
        return mb_ord(mb_convert_encoding($char, 'UCS-4BE', $encoding), 'UCS-4BE');
    }
}

function mb_htmlentities($string, $hex = false, $encoding = 'UTF-8') {
    return preg_replace_callback('/[\x{80}-\x{10FFFF}]/u', function ($match) use ($hex) {
        return sprintf($hex ? '&#x%X;' : '&#%d;', mb_ord($match[0]));
    }, $string);
}


echo mb_htmlentities(urldecode('%F0%9F%98%8E'));

This will return 😎

(note, this answer is based on a modified version of functions provided by this answer here.)