PHP的unicode转uft8函数

PHP的unicode解码函数，unicode转utf8函数

function decodeUnicode($str)
{
    return preg_replace_callback('/\\\\u([0-9a-f]{4})/i',
        create_function(
            '$matches',
            'return mb_convert_encoding(pack("H*", $matches[1]), "UTF-8", "UCS-2BE");'
        ),
        $str);
}