protected void dd1_selectedindexchanged(object sender, EventArgs e)
{
DropDownList DropDownList1 = sender as DropDownList;
GridViewRow row = (GridViewRow)DropDownList1.NamingContainer;
int rowIndex = row.RowIndex;
Label Label3= (Label)GridView1.Rows[rowIndex].FindControl("Label3");
Label lbl_price = (Label)GridView1.Rows[rowIndex].FindControl("lbl_price");
Int32 price = Convert.ToInt32(lbl_price.Text);
Int32 quantity = Convert.ToInt32(DropDownList1.SelectedValue);
String total = (Int32.Parse(quantity.ToString())* Int32.Parse(price.ToString())).ToString();
Label3.Text = total.ToString();
sumtotal();
}