Converting Unicode characters to their numeric value andor HTML entities using PHP

if (!function_exists('mb_internal_encoding')) {
    function mb_internal_encoding($encoding = NULL) {
        return ($from_encoding === NULL) ? iconv_get_encoding() : iconv_set_encoding($encoding);
    }
}

if (!function_exists('mb_convert_encoding')) {
    function mb_convert_encoding($str, $to_encoding, $from_encoding = NULL) {
        return iconv(($from_encoding === NULL) ? mb_internal_encoding() : $from_encoding, $to_encoding, $str);
    }
}

if (!function_exists('mb_chr')) {
    function mb_chr($ord, $encoding = 'UTF-8') {
        if ($encoding === 'UCS-4BE') {
            return pack("N", $ord);
        } else {
            return mb_convert_encoding(mb_chr($ord, 'UCS-4BE'), $encoding, 'UCS-4BE');
        }
    }
}

if (!function_exists('mb_ord')) {
    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');
        }
    }
}

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

if (!function_exists('mb_html_entity_decode')) {
    function mb_html_entity_decode($string, $flags = null, $encoding = 'UTF-8') {
        return html_entity_decode($string, ($flags === NULL) ? ENT_COMPAT | ENT_HTML401 : $flags, $encoding);
    }
}

echo "Get string from numeric DEC value\n";
var_dump(mb_chr(50319, 'UCS-4BE'));
var_dump(mb_chr(271));

echo "\nGet string from numeric HEX value\n";
var_dump(mb_chr(0xC48F, 'UCS-4BE'));
var_dump(mb_chr(0x010F));

echo "\nGet numeric value of character as DEC string\n";
var_dump(mb_ord('ď', 'UCS-4BE'));
var_dump(mb_ord('ď'));

echo "\nGet numeric value of character as HEX string\n";
var_dump(dechex(mb_ord('ď', 'UCS-4BE')));
var_dump(dechex(mb_ord('ď')));

echo "\nEncode / decode to DEC based HTML entities\n";
var_dump(mb_htmlentities('tchüß', false));
var_dump(mb_html_entity_decode('tchüß'));

echo "\nEncode / decode to HEX based HTML entities\n";
var_dump(mb_htmlentities('tchüß'));
var_dump(mb_html_entity_decode('tchüß'));

Get string from numeric DEC value
string(4) "ď"
string(2) "ď"

Get string from numeric HEX value
string(4) "ď"
string(2) "ď"

Get numeric value of character as DEC int
int(50319)
int(271)

Get numeric value of character as HEX string
string(4) "c48f"
string(3) "10f"

Encode / decode to DEC based HTML entities
string(15) "tchüß"
string(7) "tchüß"

Encode / decode to HEX based HTML entities
string(15) "tchüß"
string(7) "tchüß"