ASP.NET

protected void Button1_Click(object sender, EventArgs e)
    {
        if (GridView1.Rows.Count > 0)
        {
            for (int i = 0; i <= GridView1.Rows.Count - 1; i++)
            {
                TextBox qty = (TextBox)GridView1.Rows[i].FindControl("textbox2");
                Label pr = (Label)GridView1.Rows[i].FindControl("label3");
                float total = 0;
                if (!string.IsNullOrEmpty(qty.Text))
                {
                    float qty1 = float.Parse(qty.Text);

                    float pr1 = float.Parse(pr.Text);
                    total = total + (qty1 * pr1);
                }
                Label t = (Label)GridView1.FooterRow.FindControl("label3");
                t.Text = total.ToString();
            }

        }