Exporting GridView to a datatable issue

Question

I am trying to transfer grid-view data into data table.Then saving this data table to session.Why the output shown in this form

Set gridview datasource in another page

 GridView1.DataSource = (DataTable)Session["cart"];
 GridView1.DataBind();

Out Put

 Pro Name                             Unit Price    Quantity    Total Amount
System.Web.UI.WebControls.GridViewRow            
System.Web.UI.WebControls.GridViewRow   

Code

    foreach (GridViewRow row in GvProducts.Rows)
    {
        if (row.RowType == DataControlRowType.DataRow)
        {
            CheckBox chkRow = (row.Cells[0].FindControl("chkSel") as CheckBox);
            if (chkRow.Checked)
            {
                string proid = row.Cells[1].Text;
                string balance = row.Cells[3].Text;
                string proname = row.Cells[2].Text;
                string proqty = (row.Cells[5].FindControl("txtQuantity") as TextBox).Text;
                string UnitPrice = row.Cells[6].Text;
                DataTable tbl;
                if (Session["cart"] == null)
                {
                    tbl = new DataTable();
                    tbl.Columns.Add("Pro Name");
                    tbl.Columns.Add("Unit Price");
                    tbl.Columns.Add("Quantity");
                    tbl.Columns.Add("Total Amount");

                }
                else

                tbl = (DataTable)Session["cart"];
                DataRow row = tbl.NewRow();
                row[0] = proname;
                row[1] = Convert.ToDecimal(UnitPrice);
                row[2] = proqty;
                row[3] = Convert.ToInt32(proqty) * Convert.ToDecimal(UnitPrice);
                tbl.Rows.Add(row);
                Session["cart"] = tbl;
            }
        }
    }

your help is much appertained

Answer 1

@Ayman, the problem is in the below mentioned part. You provide the same variable for New Row.

  DataRow row = tbl.NewRow();
                row[0] = proname;
                row[1] = Convert.ToDecimal(UnitPrice);
                row[2] = proqty;
                row[3] = Convert.ToInt32(proqty) * Convert.ToDecimal(UnitPrice);
                tbl.Rows.Add(row);
                Session["cart"] = tbl;

Change this by,

DataRow newRow = tbl.NewRow();
                    newRow[0] = proname;
                    newRow[1] = Convert.ToDecimal(UnitPrice);
                    newRow[2] = proqty;
                    newRow[3] = Convert.ToInt32(proqty) * Convert.ToDecimal(UnitPrice);
                    tbl.Rows.Add(newRow);
                    Session["cart"] = tbl;

you have created object for "GridViewRow" and "DataRow" with same name.