xxxxxxxxxx<html><body><form runat="server">Enter a US zip code:<asp:TextBox id="txtbox1" runat="server" /><asp:Button text="Submit" OnClick="submit" runat="server" /><asp:Label id="lbl" runat="server" /><asp:RegularExpressionValidator ControlToValidate="txtbox1"ValidationExpression="d{5}"EnableClientScript="false"ErrorMessage="The zip code must be 5 numeric digits!"runat="server" /></form></body></html>