生成类似 LS14120002       
 private String GenNewOrder()

        {

            String newOrder;

            var orders = LYOrder.Items;

            String lastOrder = ((Order)orders[orders.Count - ]).OrderNum;

            //int len = lastOrder.Length;

            String dateOld = lastOrder.Substring(, );

            int indexOld = Convert.ToInt32(lastOrder.Substring(, ));

            String indexNew = (indexOld + ).ToString();

            String dateNow = System.DateTime.Now.ToString("yyMM");//获取年月

            if (dateOld.Equals(dateNow))//同一个月的单

            {

                switch (indexNew.Length)

                {

                    case :

                        indexNew = "" + indexNew;

                        break;

                    case :

                        indexNew = "" + indexNew;

                        break;

                    case :

                        indexNew = "" + indexNew;

                        break;

                }

                newOrder = " LS" + dateNow + indexNew;

            }

            else

            {

                newOrder = " LS" + dateNow + "";

            }

            return newOrder;

        }