In this article I will explain with an example, how to use ASP.Net AJAXControlToolKitt FilteredTextBoxExtender control with example.
 
 

Download and Install AJAX Control Toolkit

In order to download and install AJAXControlToolKit, please refer the following article.
Install AJAX Control Toolkit in Visual Studio ToolBox
 
 

Register AJAX Control Toolkit

You will need to register the AJAXControlToolKit assembly in order to use the AJAX Control Toolkit’s controls.
You need to place the following line just below the @Page directive.
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="cc1" %> 
 
 

Using the ASP.Net AJAX FilterTextBoxExtender control

HTML Markup

The HTML Markup consists of following controls.
ScriptManager – For enabling ASP.Net AJAX.
TextBox – For user input.
FilteredTextBoxExtender – For preventing user from entering invalid characters into TextBox.
 
The AJAX FilteredTextBoxExtender has following properties:
TargetControlID – ID of the TextBox to be validated.
FilterType – Type of filter to apply, as a comma-separated combination of Numbers, LowercaseLetters, UppercaseLetters, and Custom.
Note: If Custom is specified, the ValidChars property needs to set.
 
<asp:ScriptManager ID="ScriptManager1" runat="server" />
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender1" runat="server" FilterType="Numbers" TargetControlID="TextBox1" />
 
 

Examples

Allows only Numbers i.e. Digits 0 – 9

Following example allows only numbers i.e digits (0-9) in the TextBox.
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender1" runat="server" FilterType="Numbers" TargetControlID="TextBox1" />
 

Allows only Alphabets (Both Uppercase and Lowercase)

Following example allows only alphabets (uppercase and lowercase) in the TextBox.
<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender2" runat="server" FilterType="LowercaseLetters, UppercaseLetters" TargetControlID="TextBox2" />
 

Allows only Uppercase Alphabets

Following example allows only uppercase alphabets in the TextBox.
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender3" runat="server" FilterType="UppercaseLetters" TargetControlID="TextBox3" />
 

Allows only Lowercase Alphabets

Following example allows only lowercase alphabets in the TextBox.
<asp:TextBox ID="TextBox4" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender4" runat="server" FilterType="LowercaseLetters" TargetControlID="TextBox4" />
 

Email Address (Lower case alphabets, numbers, @ and dot)

Following example allow (lower case alphabets, numbers, @ and dot) in the TextBox.
asp:TextBox ID="TextBox5" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender5" runat="server" FilterType="Numbers, LowercaseLetters, Custom" ValidChars=".@" TargetControlID="TextBox5" />
 

Alphabets and Numbers (Alphanumeric)

Following example allows only alphabets and numbers (alphanumeric and no special characters) in the TextBox.
<asp:TextBox ID="TextBox6" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender6" runat="server" FilterType="Numbers, UppercaseLetters, LowercaseLetters" TargetControlID="TextBox6" />
 

Decimal Number (Digits and dot)

Following example allow decimal number (digits and dot) in the TextBox.
<asp:TextBox ID="TextBox7" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender7" runat="server" FilterType="Numbers, Custom" ValidChars="." TargetControlID="TextBox7" />
 

Money or Currency (Digits, comma and dot)

Following example allow money or currency (digits. Comma and dot) in the TextBox.
<asp:TextBox ID="TextBox8" runat="server"></asp:TextBox>
<cc1:FilteredTextBoxExtender ID="FilteredTextBoxExtender8" runat="server" FilterType="Numbers, Custom" ValidChars=".," TargetControlID="TextBox8" />
 
 

Demo

View Demo
 
 

Downloads

Download Code