asp.net下cookies的丟失和中文亂碼

 //寫入cookies時
string t =HttpUtility.UrlEncode(要寫入到cookies的中文值);
HttpCookie c = new HttpCookie("user_realname", t);
Response.Cookies.Add(c);
//讀取cookies時
t=獲取的中文cookies值;
t = HttpUtility.UrlDecode(teacher_name);