RegularExpressionValidator Control
Evaluates the value of an input control to determine whether it matches a pattern defined by a regular expression.
<asp:RegularExpressionValidator
id="ProgrammaticID"
ControlToValidate="ProgrammaticID of control to validate"
ValidationExpression="expression"
ErrorMessage="Message to display in ValidationSummary control"
Text="Message to display in control"
ForeColor="value"
BackColor="value"
runat="server" >
</asp: RegularExpressionValidator>
Remarks
The RegularExpressionValidator control is used to determine whether the value of an input control matches a pattern defined by a regular expression. This type of validation allows you to check for predictable sequences of characters, such as those in social security numbers, e-mail addresses, telephone numbers, postal codes, and so on.
Note If the input control is empty, no validation functions are called and validation succeeds. Use a RequiredFieldValidator control to prevent the user from skipping an input control.
Both server-side and client-side validation are performed unless the browser does not support client-side validation or client-side validation is explicitly disabled (the EnableClientScript property is set to false).
Use the ValidationExpression property to specify the regular expression used to validate input control. The regular expression validation syntax is slightly different on the client than on the server. On the client, JScript regular expression syntax is used. On the server, Regex syntax is used. Since JScript regular expression syntax is a subset of Regex syntax, it is recommended that you use JScript regular expression syntax in order to yield the same results on both the client and the server.
For additional information on creating and formatting regular expressions, see Regular Expressions.
For detailed information on the RegularExpressionValidator control, see the RegularExpressionValidator class.
Example
The following example demonstrates how to use the RegularExpressionValidator control to validate the value entered in a text box for a specific pattern. In this example, the pattern is a zip code with five digits. The validation result is then displayed on the page.
<%@ Page Language="VB" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
Sub ValidateBtn_Click(sender As Object, e As EventArgs)
If Page.IsValid Then
lblOutput.Text = "Page is Valid!"
Else
lblOutput.Text = "Page is InValid!"
End If
End Sub
</script>
</head>
<body>
<h3>RegularExpressionValidator Sample</h3>
<p>
<form runat="server">
<table bgcolor="#eeeeee" cellpadding="10">
<tr valign="top">
<td colspan="3">
<asp:Label id="lblOutput"
Text="Enter a 5 digit zip code"
Font-Name="Verdana"
Font-Size="10pt"
runat="server"/>
</td>
</tr>
<tr>
<td colspan="3">
<font <b>Personal Information</b>
</td>
</tr>
<tr>
<td align="right">
Zip Code:
</td>
<td>
<asp:TextBox id="TextBox1"
runat="server"/>
</td>
<td>
<asp:RegularExpressionValidator id="RegularExpressionValidator1"
ControlToValidate="TextBox1"
ValidationExpression="\d{5}"
Display="Static"
EnableClientScript="false"
ErrorMessage="Zip code must be 5 numeric digits"
runat="server"/>
</td>
</tr>
<tr>
<td></td>
<td>
<asp:Button text="Validate"
OnClick="ValidateBtn_Click"
runat="server"/>
</td>
<td></td>
</tr>
</table>
</form>
</body>
</html>
[C#]
<%@ Page Language="C#" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
void ValidateBtn_Click(Object sender, EventArgs e)
{
if (Page.IsValid)
{
lblOutput.Text = "Page is Valid!";
}
else
{
lblOutput.Text = "Page is InValid!";
}
}
</script>
</head>
<body>
<h3>RegularExpressionValidator Sample</h3>
<p>
<form runat="server">
<table bgcolor="#eeeeee" cellpadding="10">
<tr valign="top">
<td colspan="3">
<asp:Label id="lblOutput"
Text="Enter a 5 digit zip code"
Font-Name="Verdana"
Font-Size="10pt"
runat="server"/>
</td>
</tr>
<tr>
<td colspan="3">
<font <b>Personal Information</b>
</td>
</tr>
<tr>
<td align="right">
Zip Code:
</td>
<td>
<asp:TextBox id="TextBox1"
runat="server"/>
</td>
<td>
<asp:RegularExpressionValidator id="RegularExpressionValidator1"
ControlToValidate="TextBox1"
ValidationExpression="\d{5}"
Display="Static"
EnableClientScript="false"
ErrorMessage="Zip code must be 5 numeric digits"
runat="server"/>
</td>
</tr>
<tr>
<td></td>
<td>
<asp:Button text="Validate"
OnClick="ValidateBtn_Click"
runat="server"/>
</td>
<td></td>
</tr>
</table>
</form>
</body>
</html>
See also
RegularExpressionValidator Class | Validation Server Controls | Regular Expressions