Cookieの使用と有効期間の設定

    protected void Page_Load(object sender, EventArgs e)
    {
        //  Cookies
        HttpCookie cookie = new HttpCookie("UserName","ZhangSan");
        this.Request.Cookies.Add(cookie);

        //  Cookies   
        DateTime time = DateTime.Now;
        TimeSpan span = new TimeSpan(0, 0, 15, 0, 0);//    
        cookie.Expires = time.Add(span);//      15  

        //  Cookies
        string userName = this.Request.Cookies[0].Value;
        this.Response.Write(userName);

        //  Cookies
        this.Response.SetCookie(cookie);
    }