相信很多初学者很需这个方法，帖出来，呵呵

//{{{ utf-8截取前n个字
function Ctruncate($str = '', $len = 0, $etc = ' ...')
{
    if(0 == $len) return "";

    $str_len = preg_match_all('/[\x00-\x7F\xC0-\xFD]/', $str, $dummy);
    if($len >= $str_len)
    {
        return $str;
    }
    else
    {
        $newstr = mb_substr($str,0,$len,'utf-8');
        return $newstr.$etc;
    }
}  
//}}}