Get Gridview RowIndex on Dropdownlist or Button event inside gridview in asp.net

//****************Dropdownlist SelectedIndexChanged Event

 protected void DropDownList_SelectedIndexChanged(object sender, EventArgs e)
    {
        DropDownList ddl = (sender) as DropDownList;
        GridViewRow drr = (GridViewRow)ddl.NamingContainer;
        int rnd = drr.RowIndex;      //Row Index

//Here is your code
}


//****************Button _Click Event
 protected void Button _Click(object sender, EventArgs e)
    {
 Button Btn= (sender) as Button ;
        GridViewRow drr = (GridViewRow)Btn.NamingContainer;
       int rnd = drr.RowIndex;      //Row Index

//Here is your code
}