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ASP.NET RegularExpressionValidator Control

This validator is used to validate the value of an input control against the pattern defined by a regular expression.

It allows us to check and validate predictable sequences of characters like: e-mail address, telephone number etc.

The ValidationExpression property is used to specify the regular expression, this expression is used to validate input control.

RegularExpression Properties

Property	Description
AccessKey	It is used to set keyboard shortcut for the control.
BackColor	It is used to set background color of the control.
BorderColor	It is used to set border color of the control.
Font	It is used to set font for the control text.
ForeColor	It is used to set color of the control text.
Text	It is used to set text to be shown for the control.
ToolTip	It displays the text when mouse is over the control.
Visible	To set visibility of control on the form.
Height	It is used to set height of the control.
Width	It is used to set width of the control.
ErrorMessage	It is used to set error message that display when validation fails.
ControlToValidate	It takes ID of control to validate.
ValidationExpression	It is used to set regular expression to determine validity.

Example

Here, in the following example, we are explaining how to use RegularExpressionValidator control to validate the user input against the given pattern.

// RegularExpressionDemo.aspx

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="RegularExpressionDemo.aspx.cs" 
Inherits="asp.netexample.RegularExpressionDemo" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<table class="auto-style1">
<tr>
<td class="auto-style2">Email ID</td>
<td>
<asp:TextBox ID="username" runat="server"></asp:TextBox>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"ControlToValidate="username" 
ErrorMessage="Please enter valid email" ForeColor="Red"ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*">
</asp:RegularExpressionValidator>
</td>
</tr>
<tr>
<td class="auto-style2"></td>
<td>
<br/>
<asp:Button ID="Button1" runat="server" Text="Save"/>
</td>
</tr>
</table>
</div>
</form>
</body>
</html>

Output:

It produces the following output when view in the browser.