ASP.NET

<table>
    <tr><td valign="middle"></td>
             <td><asp:TextBox ID="cldtb" runat="server" OnTextChanged="cldtb_OnTextChanged" AutoPostBack="true"></asp:TextBox></td>
        <td valign="middle"><asp:Panel id="pnlEnterNumbers" runat="server">
           <asp:PlaceHolder id="myPlaceHolder" runat="server" /></asp:Panel> </td> </tr>

</table>

  protected void cldtb_OnTextChanged(object sender, System.EventArgs e)
  {
      int I, intNumberCount;

          // Get number of items to be entered.
          intNumberCount = System.Convert.ToInt16(cldtb.Text);

          if (intNumberCount > 0)
          {
              //Add one textbox to enter each item.
              System.Web.UI.WebControls.TextBox txtNumber;
              for (I = 1; I <= intNumberCount; I++)
              {
                  txtNumber = new System.Web.UI.WebControls.TextBox();
                  txtNumber.ID = "birthdate" + I;
                  txtNumber.MaxLength = 8;
                  myPlaceHolder.Controls.Add(txtNumber);

              }

              // Add number of items to viewstate
              ViewState["NumberCount"] = (I - 1);
              //Session["holdMe"] = myPlaceHolder;
          }
}

foreach (DataListItem dli in DataList1.Items)
        {
            CheckBox Chk = (CheckBox)dli.FindControl("CheckBox1");
            if (Chk.Checked)
            {
                str13 = "cheked";
            }
            else
            {
                str13 = "you need to check";
            }
        }
        LblErr.Visible = true;
        LblErr.Text = str13;