title: FilteredTextBoxExtender in asp.net
body: <p>iam using ajaxtoolkit in asp.net 3.5, using filter texbox extender control</p>
  
  <pre><code>                            &lt;%@ Page Language="C#" %&gt;
                          &lt;%@ Register TagPrefix="ajaxToolkit" Namespace="AjaxControlToolkit"
                          Assembly="AjaxControlToolkit" %&gt;
                          &lt;!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN"
                          “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
                          &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
                          &lt;head runat="server"&gt;
                          &lt;title&gt;Show Filtered TextBox&lt;/title&gt;
                          &lt;/head&gt;
                          &lt;body&gt;
                          &lt;form id="form1" runat="server"&gt;
                          &lt;div&gt;
                          &lt;asp:ScriptManager ID="ScriptManager1" runat="server" /&gt;
                          &lt;asp:Label
                          id="lblNumeric"
                          Text="Enter a Number:"
                          AssociatedControlID="txtNumeric"
                          Runat="server" /&gt;
                          &lt;br /&gt;
                          &lt;asp:TextBox
                          id="txtNumeric"
                          Runat="server" /&gt;
                              &lt;ajaxToolkit:FilteredTextBoxExtender ID="FilteredTextBoxExtender1" runat="server" TargetControlID="txtNumeric" FilterType="Numbers"&gt;
                              &lt;/ajaxToolkit:FilteredTextBoxExtender&gt;   
                          &lt;br /&gt;&lt;br /&gt;
                          &lt;asp:Label
                          id="lblProductCode"
                          Text="Enter a Product Code:"
                          AssociatedControlID="txtProductCode"
                          Runat="server" /&gt;
                          &lt;br /&gt;
                          &lt;asp:TextBox
                          id="txtProductCode"
                          Runat="server" /&gt;
  
                          &lt;br /&gt;
                          (A product code can contain only lower-case characters,
            ![enter image description here][1]              underscores, exclamation marks, and no spaces)
                          &lt;/div&gt;
                          &lt;/form&gt;
                          &lt;/body&gt;
                          &lt;/html&gt;
  </code></pre>
  
  <p>iam using extender control..witfiltertype as numbers..but in doesnt works at runtime,, it accepts all characters.. 
  any help would be appreciated</p>