Different Ways to Send Data Across Pages in ASP.NET.

There are various ways to pass data information across pages.

1.      Cookies

       A small piece of information or message sent by the web server to web browser during a web request, 

      which is stored on user's system in the form of a text file.

      Using a Cookie

       HttpCookie UserCookie = new HttpCookie("User");

              UserCookie.Value = txtName.Text;

              UserCookie.Expires = DateTime.Now.AddHours(1);

              Response.Cookies.Add(UserCookie);

      Retrieving a Cookie value

                    lblMsg.Text = Request.Cookies["User"].Value;

2.      QueryString

       This is another way to pass data between pages using URL. 

       e.g.: http://www.c-sharpcorner.com/Notification/Notification.aspx?Mode=out

       The section beyond part marked in red is where the query string starts, using a question mark (?) as separator. 

       Using "&" we can pass multiple query strings.

      Using a Query String

              Response.Redirect(String.Format("RetrieveData.aspx?user={0}&id={1}", txtName.Text, 1));

      Retrieving a Query String value

                    if (Request.QueryString["user"] != null) {

                     lbl2.Text = Request.QueryString["user"]; }

3.   Sessions

       The most acceptable and secure method is by using Session variables.

      Using a Session

              Session["user"] = txtName.Text;

              Session["id"] = 1;

              List<string> colors = new List<string>();

       colors.Add("red");

       colors.Add("green");

       colors.Add("blue");

       Session["colors"] = colors;

       colors = null;

              Response.Redirect("RetrieveData.aspx");

      Retrieving a Session value

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

       {

              lbl3.Text = Session["user"].ToString();

       }

       if (Session["colors"] != null)

       {

              List<string> col = new List<string>();

              col = (List<string>) Session["colors"];

              foreach (var item in col)

              {

                     lbl3.Text += " " + item + ", ";

              }

              col = null;

       }

 4. Cross-Page Posting

     Another technique used to post from one page to another page is by setting the PostBackUrl property to the target page. 

     The PreviousPage property in the target page contains a reference to the source page.

            Using Cross-Page Posting

              <asp:Button ID="btnPage2" Text="Call Page2" runat="server" width="132px" PostBackUrl="~/RetrieveData.aspx" />

            Retrieving a Cross-Page Posting value

                   if (Page.PreviousPage != null) {

                     DropDownList ddl = (DropDownList)Page.PreviousPage.FindControl("ddl1");

                     if (ddl != null) {

                           lbl4.Text = ddl.SelectedItem.Text;

                           lbl4.ForeColor = System.Drawing.Color.FromName(lbl4.Text); } }

5. Server.Transfer

    Using this technique, form values of one page can be accessed in another page by enabling second parameter to true. 

    Also, the same for the Server.Execute method.

   Using Server.Transfer

              protected void btnPage2_Click(object sender, EventArgs e) {

                     Server.Transfer("RetrieveData.aspx", true); }

           Retrieving a Server.Transfer value

                   if (Request.Form["ddl1"] != null) {

                     lbl5.Text = Request.Form["ddl1"]; }

Other ways that are used much are Submit Form, Context.Handler, Static variables, Saving data to XML, Text file etc.. 

or a Database and later retrieve it another form.