<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm7.aspx.cs" Inherits="WebApplication17.WebForm7" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
</div>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"
ControlToValidate="TextBox1" ErrorMessage="Only numbers"
ValidationExpression="^\d+$"></asp:RegularExpressionValidator>
</form>
</body>
</html>