protected void Page_Load(object sender, EventArgs e)

        {

            if (!IsPostBack)

            {

                Sessioninfo();

            }

            Session.Remove("info");

        }

		 private void Sessioninfo()

        {

            if (Session["info"] != null)

                tc.Text = Session["info"].ToString();

        }

		   private void  sessionadd() {

            Session.Add("info", tc.Text);

        }

		//事件中添加

		 sessionadd();