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protected void AddProductToSession(object sender, EventArgs e)

{

Bill product1 = new Bill(Productname.Text, int.Parse(ProductID.Text), int.Parse(quantityProduct.Text), int.Parse(UnitPrice.Text), int.Parse(TotalPrice.Text));

InvoiceModel invoiceNew = null;

invoiceNew = (InvoiceModel)Session["InvoiceModel"];

//invoiceNew = invoicemodel;

invoiceNew.bill.Add(product1);

ProductTableInvoice.Visible = true;

String txt = "";

txt += """";""";

#	Product Name	Quantity	Unit Price	Total Price	Control
" + (i + 1) + "	" + invoiceNew.bill[i].Productname + "	" + invoiceNew.bill[i].quantity + "	" + invoiceNew.bill[i].Unitprice + "	" + invoiceNew.bill[i].totalAmount + "	" + "Delete

";

ProductTableInvoice.InnerHtml = txt;

Session["InvoiceModel"] = invoiceNew;

//invoicemodel = invoiceNew;

SubmitButtonDiv.Visible = true;

}