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CheckBox Class

Displays a check box that allows the user to select a true or false condition.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

'Declaration
<ControlValuePropertyAttribute("Checked")> _
<AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
<AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level := AspNetHostingPermissionLevel.Minimal)> _
Public Class CheckBox _
	Inherits WebControl _
	Implements IPostBackDataHandler, ICheckBoxControl
'Usage
Dim instance As CheckBox
<asp:CheckBox />

Use the CheckBox control to allow the user to select a true or false state.

If you plan to use multiple CheckBox controls, the CheckBoxList control is an alternative control that provides convenient data binding capabilities. However, individual CheckBox controls provide greater control over layout.

Security noteSecurity Note:

A CheckBox control accepts user input, which is a potential security threat. By default, ASP.NET mobile Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.

Accessibility

The markup rendered by default for this control might not conform to accessibility standards such as the Web Content Accessibility Guidelines 1.0 (WCAG) priority 1 guidelines. For details about accessibility support for this control, see ASP.NET Controls and Accessibility.

The following example demonstrates how to use a CheckBox control to indicate whether tax is included in the calculation for a sales total.

NoteNote:

The following code sample uses the single-file code model and may not work correctly if copied directly into a code-behind file. This code sample must be copied into an empty text file that has an .aspx extension. For more information on the Web Forms code model, see ASP.NET Web Page Code Model.

<%@ Page Language="VB" 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 runat="server">
    <title>CheckBox CheckedChanged Example</title>
<script runat="server">

      Sub Check_Clicked(sender As Object, e As EventArgs) 

         ' Calculate the subtotal and display the result in currency format. 
         ' Include tax if the check box is selected.
         Message.Text = CalculateTotal(checkbox1.Checked).ToString("c")

      End Sub 

      Sub Page_Load(sender As Object, e As EventArgs)

         ' Display the subtotal without tax when the page is first loaded. 
         If Not IsPostBack Then 

            ' Calculate the subtotal and display the result in currency format.
            Message.Text = CalculateTotal(false).ToString("c")

         End If 

      End Sub 

      Function CalculateTotal(Taxable As Boolean) As Double  

         ' Calculate the subtotal for the example. 
         Dim Result As Double = 1.99 + 2.99 + 3.99

         ' Add tax, if applicable. 
         If(Taxable)

            Result += Result * 0.086

         End If 

         Return Result 

      End Function

   </script>

</head>

<body>

   <form id="form1" runat="server">

      <h3>CheckBox CheckedChanged Example</h3>

      Select whether to include tax in the subtotal.

      <br /><br />

      <table border="1" cellpadding="5">

         <tr>

            <th colspan="2">

               Shopping cart

            </th>

         </tr>

         <tr>

            <td>

               Item 1

            </td>

            <td>

               $1.99

            </td>

         </tr>

         <tr>

            <td>

               Item 2

            </td>

            <td>

               $2.99

            </td>

         </tr>

         <tr>

            <td>

               Item 3

            </td>

            <td>

               $3.99

            </td>

         </tr>

         <tr>

            <td>

               <b>Subtotal</b>

            </td>

            <td>

               <asp:Label id="Message" runat="server"/>

            </td>

         </tr>

         <tr>

            <td colspan="2">

               <asp:CheckBox id="checkbox1" runat="server"
                    AutoPostBack="True"
                    Text="Include 8.6% sales tax"
                    TextAlign="Right"
                    OnCheckedChanged="Check_Clicked"/>

            </td>

         </tr>

      </table>

   </form>

</body>

</html>

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

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