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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 the same value for the GroupName property. Users can select one radio button at a time within a radio button group. GroupName property specifies 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 allows us to write an event handler for the RadioButton CheckedChanged event.

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

RadioButton Checked property gets or sets a value that indicates whether the RadioButton control is checked. The following ASP.NET c# example code demonstrates to us how can we use the CheckedChanged event in RadioButton server control.

In this example code, we create two RadioButton server controls and use the same name for the GroupName property. We write only an event handler for both RadioButtons CheckedChanged events. When the user changes the selection of a RadioButton in this RadioButton group then the CheckedChaged event raises and we can determine programmatically both RadioButton's current checked status.
RadioButtonOnCheckedChanged.aspx

<%@ Page Language="C#" %>

<!DOCTYPE html>

<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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