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ASP.NET Alpha Numeric Validation Using RegularExpressionValidator

ASP.NET RegularExpressionValidator is useful to allow user to enter only alpha numeric value and display error for any other special character found. The RegularExpressionValidator control belongs to System.Web.UI.WebControls


<asp:RegularExpressionValidator ID="regularExp" runat="server" 
ValidationExpression="^[a-zA-Z0-9 ]*$" 
ErrorMessage="Invalid text, enter only 0-9 and a-z or A-Z character."></asp:RegularExpressionValidator>

ASP.NET RegularExpressionValidator Control Property

ControlToValidateSpecifies control name which needs to be validate.
DisplaySpecifies behavior of the error message.
EnableClientScriptSpecifies whether or not client-side validation is enabled.
EnabledSpecifies whether or not validation control is enabled or not.
ErrorMessageSpecifies error messageto be display in validation summary.
ForeColorSpecifies error message color.
IsValidIndicate if associate control passes validation or not.
SetFocusOnErrorSet focus on associate control if validation fails.
TextSpecifies text to be display if validation fails.
ValidationGroupSpecifies validation group name.
ValidateUpdate the isvalid propery.
ValidateGetValidationPropertyDetermineing validation property of a control, if it exists.
ValidationExpressionSpecifies regular expression that you want to match against input value.

ASP.NET Alpha Numeric Validation Using RegularExpressionValidator Example

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" 
Inherits="_Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>ASP.NET Alpha Numeric Validation Example</title>
<form id="Form" runat="server">
<div style="width: 619px">
<asp:Label ID="lblTitle" runat="server" Font-Bold="True" Font-Size="Medium" 
Font-Underline="True" Text="ASP.NET Alpha Numeric Validation Example"></asp:Label>
<table border="0" width="600px" cellpadding="0" cellspacing="0">
<asp:Label ID="lblZip" runat="server" Font-Bold="True" Font-Size="Small" 
Text="Enter Text:"></asp:Label>
<asp:TextBox ID="TextBox4" runat="server" Width="177px"></asp:TextBox>
<asp:RegularExpressionValidator ID="RegularExpressionValidator4" runat="server" 
ControlToValidate="TextBox4" ErrorMessage="Invalid text, enter only 0-9 and a-z or A-Z character." 
ValidationExpression="^[a-zA-Z0-9 ]*$"></asp:RegularExpressionValidator>
<asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" 
ControlToValidate="TextBox4" ErrorMessage="This required field, can not be blank."></asp:RequiredFieldValidator>
<asp:Button ID="btnSubmit" runat="server" Font-Bold="True" 
Font-Size="Small" Text="Submit" Width="60px" />

Above example will produce following output