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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)

[ThemeableAttribute(false)] 
public virtual int MaxLength { get; set; }
/** @property */
public int get_MaxLength ()

/** @property */
public void set_MaxLength (int value)

public function get MaxLength () : int

public function set MaxLength (value : int)

Not applicable.

Property Value

The maximum number of characters allowed in the text box. The default is 0, which indicates that the property is not set.

Exception typeCondition

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.

NoteNote:

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 Introduction to ASP.NET Themes.

TopicLocation
How to: Set ASP.NET Web Server Control PropertiesBuilding ASP .NET Web Applications
How to: Set ASP.NET Web Server Control PropertiesBuilding 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 noteSecurity 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 (Visual Studio).

<%@ 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">

               &nbsp;

            </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>

               &nbsp
 
            </td>

         </tr>

         <tr align="center">

            <td colspan="4">

               <asp:Button ID="AddButton"
                    Text="Add"
                    OnClick="AddButton_Click"
                    runat="server"/>

            </td>

            <td>

               &nbsp;

            </td>

         </tr>

      </table>

   </form>

</body>
</html>

Windows 98, Windows Server 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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