TextBox.MaxLength Property
Gets or sets the maximum number of characters allowed in the text box.
Namespace: System.Web.UI.WebControls
Assembly: System.Web (in System.Web.dll)
| Exception | Condition |
|---|---|
| ArgumentOutOfRangeException | The specified width is less than 0. |
Use the MaxLength property to limit the number of characters that can be entered in the TextBox control.
 Note |
|---|
This property is applicable only when the TextMode property is set to TextBoxMode.SingleLine or TextBoxMode.Password. |
This property cannot be set by themes or style sheet themes. For more information, see ThemeableAttribute and ASP.NET Themes and Skins.
| Topic | Location |
|---|---|
| How to: Set ASP.NET Web Server Control Properties | Building ASP .NET Web Applications |
| How to: Set ASP.NET Web Server Control Properties | Building ASP .NET Web Applications |
The following code example demonstrates how to use the MaxLength property to limit the number of characters allowed in the TextBox control to 3.
| Security Note |
|---|
This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview. |
<%@ Page Language="C#" AutoEventWireup="True" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head> <title> TextBox Example </title> <script runat="server"> protected void AddButton_Click(Object sender, EventArgs e) { int Answer; Answer = Convert.ToInt32(Value1.Text) + Convert.ToInt32(Value2.Text); AnswerMessage.Text = Answer.ToString(); } </script> </head> <body> <form id="form1" runat="server"> <h3> TextBox Example </h3> <table> <tr> <td colspan="5"> Enter integer values into the text boxes. <br /> Click the Add button to add the two values. <br /> Click the Reset button to reset the text boxes. </td> </tr> <tr> <td colspan="5"> </td> </tr> <tr align="center"> <td> <asp:TextBox ID="Value1" Columns="2" MaxLength="3" Text="1" runat="server"/> </td> <td> + </td> <td> <asp:TextBox ID="Value2" Columns="2" MaxLength="3" Text="1" runat="server"/> </td> <td> = </td> <td> <asp:Label ID="AnswerMessage" runat="server"/> </td> </tr> <tr> <td colspan="2"> <asp:RequiredFieldValidator ID="Value1RequiredValidator" ControlToValidate="Value1" ErrorMessage="Please enter a value.<br />" Display="Dynamic" runat="server"/> <asp:RangeValidator ID="Value1RangeValidator" ControlToValidate="Value1" Type="Integer" MinimumValue="1" MaximumValue="100" ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />" Display="Dynamic" runat="server"/> </td> <td colspan="2"> <asp:RequiredFieldValidator ID="Value2RequiredValidator" ControlToValidate="Value2" ErrorMessage="Please enter a value.<br />" Display="Dynamic" runat="server"/> <asp:RangeValidator ID="Value2RangeValidator" ControlToValidate="Value2" Type="Integer" MinimumValue="1" MaximumValue="100" ErrorMessage="Please enter an integer <br /> between than 1 and 100.<br />" Display="Dynamic" runat="server"/> </td> <td>   </td> </tr> <tr align="center"> <td colspan="4"> <asp:Button ID="AddButton" Text="Add" OnClick="AddButton_Click" runat="server"/> </td> <td> </td> </tr> </table> </form> </body> </html>
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
