我正在用 C# WPF 做一个项目我想将 Datagrid 的两列相乘并在最后总结总列值，如果 Datagrid 中有产品可用，那么当我扫描条形码时，它会增加产品的数量在购物车中这是我的观点

private void Scanner()
{
    try
    {
        if (tbProduct.Text == "")
        {
            MessageBox.Show("Please Scan barcode..","message",MessageBoxButton.OK,MessageBoxImage.Information);
        }
        else
        {

            IEnumerable<tbl_Product> tbl_s = pr.Getall();
            foreach (var item in tbl_s)
            {
                if (item.Barcode == tbProduct.Text)
                {

                    if (Convert.ToDouble(item.InStock) <= 0)
                    {
                        MessageBox.Show("Product is out of Stock",MessageBoxImage.Information);
                    }
                    else
                    {
                        for (int i = 0; i <= dgvcust.Items.Count; i++)
                        {
                            if ((dgvcust.Columns[0].getcellContent(dgvcust.Items[i]) as TextBlock).Text != item.Product_Name)
                            {
                                dgvcust.Items.Add(new { Name = item.Product_Name,Price = item.Sales_Price,Qty = 1 });
                                decimal sum = 0;

                                (dgvcust.Columns[3].getcellContent(dgvcust.Items[i]) as TextBlock).Text = (decimal.Parse((dgvcust.Columns[2].getcellContent(dgvcust.Items[i]) as TextBlock).Text) * decimal.Parse((dgvcust.Columns[1].getcellContent(dgvcust.Items[i]) as TextBlock).Text)).ToString();

                                sum += decimal.Parse((dgvcust.Columns[3].getcellContent(dgvcust.Items[i]) as TextBlock).Text);
                                TbTotalGrand.Text = sum.ToString();
                                //(dgvcust.Columns[3].getcellContent(dgvcust.Items[i]) as TextBlock).Text =   (decimal.Parse((dgvcust.Columns[2].getcellContent(dgvcust.Items[i]) as TextBlock).Text) * (decimal.Parse((dgvcust.Columns[1].getcellContent(dgvcust.Items[i]) as TextBlock).Text))).ToString();

                            }
                            else
                            {
                                (dgvcust.Columns[1].getcellContent(dgvcust.Items[i]) as TextBlock).Text = 1 + (dgvcust.Columns[1].getcellContent(dgvcust.Items[i]) as TextBlock).Text;
                            }
                        }
                    }
                }
            }
        }
    }
    catch { }
}