动态网格视图中的计算？

Question

  if(ddlindentno.SelectedItem.Text != "--Select--")
    {            
        foreach (GridViewRow row in GVFeedsaleOrder.Rows)
        {
            DropDownList ddl = (DropDownList)row.FindControl("ddltype");
            DropDownList ddl1 = (DropDownList)row.FindControl("ddlqty");
            TextBox txtnufbags = (TextBox)row.FindControl("txtnoofbags");
            TextBox txtrateperkg = (TextBox)row.FindControl("txtrateperkg");


            if (txtnufbags.Text.Trim() != "" && txtrateperkg.Text.Trim() != "" && ddl.SelectedItem.Text != "--Select--" && ddl1.SelectedItem.Text != "--Select--")
            {
                //CalculateTotal();
                objfeedretailPL.sno = Convert.ToInt32(ddlindentno.SelectedValue);
                objfeedretailPL.type = Convert.ToInt32(ddl.SelectedValue);
                objfeedretailPL.quantity = Convert.ToInt32(ddl1.SelectedItem.Text);
                objfeedretailPL.noofbags = Convert.ToInt32(txtnufbags.Text.ToString());
                objfeedretailPL.rateperkg = Convert.ToSingle(txtrateperkg.Text.ToString());                      
                objfeedretailPL.username = Session["username"].ToString();


                int baginkgs = Convert.ToInt32(ddl1.SelectedItem.Text);
                int noofbags = Convert.ToInt32(txtnufbags.Text);
                float ratepkg = Convert.ToSingle(txtrateperkg.Text);

                float recamt = Convert.ToSingle(lblamtrec.Text.ToString());

           //    ArrayList arr = new ArrayList();


                if ((noofbags * ratepkg * ratepkg) <= recamt)
                {
                    DataTable dtinsertconfirmindent = new DataTable();
                    dtinsertconfirmindent = objfeedretailBAL.GetFsindenconfirmtDetails(objfeedretailPL);
                }
                else
                {
                    ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "Message", "alert('Please Check Amount Details');", true);
                }

            }
        }

        FirstGridViewRow();

    }

我想用arraylist计算“ddl1”，txtnuffbags，txtrateperkg值的每一行.. 如何添加它。请帮帮我