Introduction
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, individualCheckBox controls provide greater control over layout.
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.
The following example demonstrates how to use a CheckBox control to indicate whether tax is included in the calculation for a sales total.
<%@ 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 runat="server"> <title>CheckBox CheckedChanged Example</title> <script runat="server"> void Check_Clicked(Object sender, EventArgs e) { // 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"); } void Page_Load(Object sender, EventArgs e) { // Display the subtotal without tax when the page is first loaded. if(!IsPostBack) { // Calculate the subtotal and display the result in currency format. Message.Text = CalculateTotal(false).ToString("c"); } } double CalculateTotal(bool Taxable) { // Calculate the subtotal for the example. double Result = 1.99 + 2.99 + 3.99; // Add tax, if applicable. if(Taxable) { Result += Result * 0.086; } return Result; } </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>
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