protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
               //。。。。。
                GridViewRow row = e.Row;
    Users users_child = row.DataItem as Users;
                users_child.daysCount = count;//重新某单元格值 
             }
}

(e.Row. DataItem as Users). daysCount=count;