how to calculate total price using grid view values

int qty = 0;
int amount = 0;
int rowTotal = 0;
int subTotal = 0;
int total = 0;
foreach(GridViewRow row in GridView1.Rows)
{
   qty = Convert.ToInt32(row.Cells[0].Text); //replace 0 with row cell index of qty
   amount = Convert.ToInt32(row.Cells[1].Text); //replace 1 with row cell index of amount
   rowTotal = qty * amount;   
   subTotal += rowTotal
}
total = subTotal;
Label1.Text = total.ToString();