$str = "中华人民共和国";

        $len = mb_strlen($str,'utf-8');

        if($len>=6){

            $str1 = mb_substr($str,0,2,'utf-8');

            $str2 = mb_substr($str,$len-2,2,'utf-8');

        }

        else{

            $str1 = mb_substr($str,0,1,'utf-8');

            $str2 = mb_substr($str,$len-1,1,'utf-8');

        }

        $this->assign('str1',$str1);

        $this->assign('str2',$str2);

        $this->assign('str',$str1.'**'.$str2);

        $this->assign('strold',substr_replace($str,'**',2,2));