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RadioButton OnCheckedChanged event in asp.net

CheckedChanged event in RadioButton
RadioButton is an asp.net web server control. radio buttons are grouped logically when they share same value for GroupName property. user can select one radio button at a time within a radio button group. GroupName property specify a grouping of radio buttons to create a mutually exclusive set of controls.

RadioButton OnCheckedChanged method raises the CheckedChanged event of radiobutton control. this method allow us to write an event handler for radiobutton CheckedChanged event.

radiobutton CheckedChanged event occurs when the Checked property value changes between posts to the server. this event only work when we set the radiobutton AutoPostBack property value to true. by using this event we can determine the checked status of radiobutton immediately after user change selection of radiobutton.

radiobutton Checked property get or set a value which indicate whether the radiobutton control is checked. the following asp.net c# example code demonstrate us how can we use CheckedChanged event in radiobutton server control.

in this example code we create two radiobutton server controls and uses same name for GroupName property. we write only an event handler for both radiobuttons CheckedChanged event. when user change selection of a radiobutton in this radiobutton group then the CheckedChaged event raise and we can determine programmatically both radiobuttons current checked status.
RadioButtonOnCheckedChanged.aspx
<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">
    protected void RadioButton_CheckedChanged(object sender, System.EventArgs e)
    {
        if (RadioButton1.Checked == true)
        {
            Label1.Text = "You choose: " + RadioButton1.Text;
        }
        else
        {
            Label1.Text = "You choose: " + RadioButton2.Text;
        }
    }
</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>How to use OnCheckedChanged event in RadioButton</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <h2 style="color:Navy">RadioButton Example: OnCheckedChanged</h2>
        <asp:Label 
             ID="Label1"
             runat="server"
             Font-Bold="true"
             ForeColor="OliveDrab"
             Font-Size="Large"
             >
        </asp:Label>
        <br /><br />
        <asp:Label 
             ID="Label2"
             runat="server"
             Font-Bold="true"
             ForeColor="Crimson"
             Text="Favorite Control?"
             >
        </asp:Label>
        <br />
        <asp:RadioButton 
             ID="RadioButton1" 
             runat="server"
             Text="ValidationSummary"
             GroupName="Controls"
             OnCheckedChanged="RadioButton_CheckedChanged"
             AutoPostBack="true"
             />
        <asp:RadioButton 
             ID="RadioButton2" 
             runat="server"
             Text="CompareValidator"
             GroupName="Controls"
             OnCheckedChanged="RadioButton_CheckedChanged"
             AutoPostBack="true"
             />
    </div>
    </form>
</body>
</html>
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