记录DataGird的整行数据之和及动态创建列后赋值和

            List<string> num = new List<string>();
            try
            {
                for (int i = 0; i < DataGrid1.Rows.Count - 1; i++)
                {
                    double aa = 0;
                    for (int j = 1; j < DataGrid1.Columns.Count; j++)
                    {
                        double bb = Convert.ToDouble(DataGrid1.Rows[i].Cells[j].Value);
                        aa += bb;
                    }
                    num.Add(aa.ToString());
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }

/////////////////////////////////////////////////////////////

            DataGridViewTextBoxColumn QuantityColumn = new DataGridViewTextBoxColumn();
            QuantityColumn.Name = "Quantity";
            QuantityColumn.HeaderText = "总计";
            QuantityColumn.Width = 100;
            QuantityColumn.SortMode = DataGridViewColumnSortMode.Automatic;
            dgGoodsSale.Columns.Add(QuantityColumn);

            for (int i = 0; i < dgGoodsSale.Rows.Count-1;i++)
            {
                this.dgGoodsSale.Rows[i].Cells["Quantity"].Value = Convert.ToDouble(num[i]);
            }