.net Cookieを追加する4つの方法

//     Cookie  
        HttpCookie myCookie = new HttpCookie("userrole");
        myCookie.Values["a"] = "a";
        myCookie.Values[""] = "b";
        myCookie.Expires.AddDays(1);
        Response.Cookies.Add(myCookie);
        //Response.AppendCookie(mycookie);       
        //     Cookie  
        Response.Write(Request.Cookies["userrole"].Values["a"].ToString());
        //     Cookie  
        HttpCookie myCookie = new HttpCookie("userrole");
        myCookie.Values["a"] = "a";
        myCookie.Values["b"] = "b";
        myCookie.Expires.AddDays(1);
        Response.Cookies.Add(myCookie);
        //     Cookie  
        HttpCookie cookie = Request.Cookies["userrole"];
        Response.Write(cookie.Values["a"].ToString());
        Response.Write(cookie.Values["b"].ToString());
        //     Cookie  
        HttpCookie myCookie = new HttpCookie("userrole");
        myCookie.Value = "a";
        Response.Cookies.Add(myCookie);
        //     Cookie  
        Response.Write(Request.Cookies["userrole"].Value);
        //     Cookie  
        HttpContext.Current.Response.Cookies.Add(new HttpCookie("userrole", "     "));
        Response.Cookies["userrole"].Value = "     ";
        HttpCookie cookie = Request.Cookies["userrole"];
        Response.Write(cookie.Value);
        //     Cookie  
        Response.Write(Request.Cookies["userrole"].Value);