Linq 2

 List lstComm = COMMUNE_DAO.GetAll().Where(comm => comm.Id_pays == 5).ToList();
                List lstCanton = CANTON_DAO.GetAll().ToList();

                var res = from com in lstComm
                          join can in lstCanton on com.Code_canton equals can.Code_canton
                          select new
                          {
                              com.Nomcom,
                              can.Nomcant
                          };

                foreach (var elem in res)
                {
                    string chaine =elem.Nomcant + elem.Nomcom ;
                }