php 字符串超出限定显示省略号

 $len){
                $str= mb_substr($str,0,$len,'utf-8').$suffix;
            }
            return $str;
        }else{
            if(strlen($str) > $len){
                $str= substr($str,0,$len,'utf-8').$suffix;
            }
            return $str;
        }         
    }
?>