php版本的charCodeAt()函数

function get_bianma($str)//等同于js的charCodeAt()  
{  
    $result = array();  
    for($i = 0, $l = mb_strlen($str, 'utf-8');$i < $l;++$i)  
    {  
        $result[] = uniord(mb_substr($str, $i, 1, 'utf-8'));  
    }  
    return join(",", $result);  
}  
function uniord($str, $from_encoding = false)  
{  
    $from_encoding = $from_encoding ? $from_encoding : 'UTF-8';  
    if (strlen($str) == 1)  
        return ord($str);  
    $str = mb_convert_encoding($str, 'UCS-4BE', $from_encoding);  
    $tmp = unpack('N', $str);  
    return $tmp[1];  
}