How to convert Bytes(UTF-8) to Unicode in php?

Question

How can i convert

\xF0\x9F\x98\x83

to

\u1F603

in php?

PS: it's a Emoji -> 😃, i need Unicode to use Twemoji.

Answer 1

Interesting, not much is out there for PHP. There seems to be a promising post, but unfortunately the accepted answer gives incorrect results in Your case.

So here's a revised version of Adam's solution rewritten in PHP.

/**
 * Translates a sequence of UTF-8 bytes to their equivalent unicode code points.
 * Each code point is prefixed with "\u".
 *
 * @param string $utf8
 *
 * @return string
 */
function utf8_to_unicode($utf8) {
    $i = 0;
    $l = strlen($utf8);

    $out = '';

    while ($i < $l) {
        if ((ord($utf8[$i]) & 0x80) === 0x00) {
            // 0xxxxxxx
            $n = ord($utf8[$i++]);
        } elseif ((ord($utf8[$i]) & 0xE0) === 0xC0) {
            // 110xxxxx 10xxxxxx
            $n =
                ((ord($utf8[$i++]) & 0x1F) <<  6) |
                ((ord($utf8[$i++]) & 0x3F) <<  0)
            ;
        } elseif ((ord($utf8[$i]) & 0xF0) === 0xE0) {
            // 1110xxxx 10xxxxxx 10xxxxxx
            $n =
                ((ord($utf8[$i++]) & 0x0F) << 12) |
                ((ord($utf8[$i++]) & 0x3F) <<  6) |
                ((ord($utf8[$i++]) & 0x3F) <<  0)
            ;
        } elseif ((ord($utf8[$i]) & 0xF8) === 0xF0) {
            // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
            $n =
                ((ord($utf8[$i++]) & 0x07) << 18) |
                ((ord($utf8[$i++]) & 0x3F) << 12) |
                ((ord($utf8[$i++]) & 0x3F) <<  6) |
                ((ord($utf8[$i++]) & 0x3F) <<  0)
            ;
        } elseif ((ord($utf8[$i]) & 0xFC) === 0xF8) {
            // 111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
            $n =
                ((ord($utf8[$i++]) & 0x03) << 24) |
                ((ord($utf8[$i++]) & 0x3F) << 18) |
                ((ord($utf8[$i++]) & 0x3F) << 12) |
                ((ord($utf8[$i++]) & 0x3F) <<  6) |
                ((ord($utf8[$i++]) & 0x3F) <<  0)
            ;
        } elseif ((ord($utf8[$i]) & 0xFE) === 0xFC) {
            // 1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
            $n =
                ((ord($utf8[$i++]) & 0x01) << 30) |
                ((ord($utf8[$i++]) & 0x3F) << 24) |
                ((ord($utf8[$i++]) & 0x3F) << 18) |
                ((ord($utf8[$i++]) & 0x3F) << 12) |
                ((ord($utf8[$i++]) & 0x3F) <<  6) |
                ((ord($utf8[$i++]) & 0x3F) <<  0)
            ;
        } else {
            throw new \Exception('Invalid utf-8 code point');
        }

        $n = strtoupper(dechex($n));
        $pad = strlen($n) <= 4 ? strlen($n) + strlen($n) %2 : 0;
        $n = str_pad($n, $pad, "0", STR_PAD_LEFT);

        $out .= sprintf("\u%s", $n);
    }

    return $out;
}

---

And in your case

php > var_dump(utf8_to_unicode("\xF0\x9F\x98\x83"));
string(7) "\u1F603"

Answer 2

Use a combination of:

1. stripcslashes() to convert \xFF byte escapes.
   That'll result in a string of UTF-8, because that's what it seemingly was originally.

2. json_encode() to convert "😃" back to an \uFFFF Unicode escape.
   If that's what you want to end up with. (Not enough context in your question to tell.)