php chr with unicode values

Can I use unicode value of a ch开发者_如何学Goaracter (for example U+0021 for !) in php? and convert it to original character in printing (with chr() or other functions)?

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function replace_unicode_escape_sequence($match) {
    return mb_convert_encoding(pack('H*', $match[1]), 'UTF-8', 'UCS-2BE');
}
function unicode_chr ($chr) {
    $x = explode("+", $chr);
    $str = "\u".end($x);
    return preg_replace_callback('/\\\\u([0-9a-f]{4})/i', 'replace_unicode_escape_sequence', $str);
}

var_dump(unicode_chr("U+0021")); // string(1) "!"

Adapted from: How to decode Unicode escape sequences like "\u00ed" to proper UTF-8 encoded characters?