In this article I will explain with an example, how to use Regular Expression (Regex) to accept/allow Alphanumeric characters i.e. Alphabets (Upper and Lower case) and Numbers (Digits) and Special Characters in TextBox in ASP.Net using:-
1. RegularExpression Validator.
2. JavaScript.
3. jQuery.
1. Regular Expression to accept Alphanumeric (Alphabets and Numbers) and Special Characters in TextBox using RegularExpression Validator
The following HTML Markup consists of a TextBox, a Button and a RegularExpression Validator which has been applied with the Regular Expression (Regex) to accept only Alphanumeric characters i.e. Alphabets (Upper and Lower case) and Numbers (Digits) and the specified Special Characters as valid characters.
<asp:TextBox ID="TextBox1" runat="server" />
<br />
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="TextBox1"
ForeColor="Red" ValidationExpression="[a-zA-Z0-9%*#]*$" ErrorMessage="Valid characters: Alphabets, Numbers and '%*#' characters." />
<br />
<asp:Button ID="Button1" Text="Validate" runat="server" />
2. Regular Expression to accept Alphanumeric (Alphabets and Numbers) and Special Characters in TextBox using JavaScript
The following HTML Markup consists of a TextBox, a Button and an HTML SPAN. On the OnClientClick event of the Button, a JavaScript function is executed which validates the TextBox text against the Regular Expression (Regex) and if it contains character other than Alphabets, Numbers or the specified Special Characters then an error message is displayed.
<asp:TextBox ID="TextBox2" runat="server" />
<br />
<span id="spnError" style="color: Red; display: none">Valid characters: Alphabets, Numbers and '%*#' characters.</span>
<br />
<asp:Button ID="Button2" Text="Validate" runat="server" CausesValidation="false"
OnClientClick="return Validate()" />
<script type="text/javascript">
function Validate() {
var isValid = false;
var regex = /^[a-zA-Z0-9%*#]*$/;
isValid = regex.test(document.getElementById("<%=TextBox2.ClientID %>").value);
document.getElementById("spnError").style.display = !isValid ? "block" : "none";
return isValid;
}
</script>
3. Regular Expression to accept Alphanumeric (Alphabets and Numbers) and Special Characters in TextBox using jQuery
The following HTML Markup consists of a TextBox, a Button and an HTML SPAN. To the Button a jQuery click event handler is attached thus when the button is clicked, the TextBox text is validated against the Regular Expression (Regex) and if it contains character other than Alphabets, Numbers or the specified Special Characters then an error message is displayed.
<asp:TextBox ID="TextBox3" runat="server" />
<br />
<span id="spnError2" style="color: Red; display: none">*Valid characters: Alphabets, Numbers and '%*#' characters.</span>
<br />
<asp:Button ID="btnValidate" Text="Validate" runat="server" CausesValidation="false" />
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
$(function () {
$("[id*=btnValidate]").bind("click", function () {
var isValid = false;
var regex = /^[a-zA-Z0-9%*#]*$/;
isValid = regex.test($("[id*=TextBox3]").val());
$("#spnError2").css("display", !isValid ? "block" : "none");
return isValid;
});
});
</script>
Screenshot
![Regular Expression to accept Alphanumeric (Alphabets and Numbers) and Special Characters in TextBox in ASP.Net]()
Demo
Browser Compatibility
The above code has been tested in the following browsers.
![Internet Explorer]()
![FireFox]()
![Chrome]()
![Safari]()
![Opera]()
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