How do i convert this code snippet to c#

Question

I am trying to figure out how to display confirm box when drop down list's selected indexchanged event is fired.

Browsing thru some forum I came across the following solution but I dont know how I can use it as I am working in c#. How do I make it work? I am not even sure if this is really the solution to my problem. Some one please help.Thanks.

Public Sub ConfirmOnChange()
            'Register the script block
            If Not IsStartupScriptRegistered("CSP-ddl-onchange") Then
                RegisterStartupScript("CSP-ddl-onchange", _
                    "<script language=""JavaScript"">" & _
                    "var CSP_savedDDLID = " & _
                     "document.getElementById('" & _
                     ddl.ClientID & "').value;" & vbCrLf & _
                    "function resetDDLIndex() {" & vbCrLf & _
                    " document.getElementById('" & _
                     ddl_Status.ClientID & "').value = CSP_savedDDLID;" & _
                    vbCrLf & _
                    "}" & vbCrLf & _
                    "</script>")
            End If
            Dim msg As String = "'Do you want to change selection?';"
            ddl_Status.Attributes("onchange") = _
            "if (!confirm('" & msg.Replace("'", "\'") & _
            "')) resetDDLIndex(); "
        End Sub

Answer 1

public void ConfirmOnChange()
{
    //Register the script block
    if(!IsStartupScriptRegistered("CSP-ddl-onchange"))
    {
        RegisterStartupScript("CSP-ddl-onchange",
            "<script language=\"JavaScript\">" +
            "var CSP_savedDDLID = " +
                "document.getElementById('" +
                ddl.ClientID + "').value;" + "\r\n" +
            "function resetDDLIndex() {" + "\r\n" +
            " document.getElementById('" +
                ddl_Status.ClientID + "').value = CSP_savedDDLID;" +
            "\r\n" +
            "}" + "\r\n" +
            "</script>");
    }
    string msg = "'Do you want to change selection?';";
    ddl_Status.Attributes("onchange") = "if (!confirm('" & msg.Replace("'", "\'") +
    "')) resetDDLIndex(); ";
}