如何基于GridView中的所选复选框计算总和

int c =1;
int sum =0;

foreach (GridView row in GridView.Rows)
            {
                CheckBox cb = row.FindControl("chkStatus");
                //Find checkbox control
                //Only the controls that are checked
                if (cb != null && cb.Checked)
                {
                    sum = sum + row.Cells(c).Text;
                    //Sum previous cell value plus every next selected drow cell value

                    // Set the sum label text value

                }
            }

 txtSelected.Text = sum.ToString();