Mine

                // Check if we should rename ALL rows
                DataGridViewRowCollection rows;
                if (renameAll)
                {
                    rows = dataGridView1.Rows;
                }
                else
                {
                    foreach (DataGridViewRow row in dataGridView1.SelectedRows)
                    {
                        rows.Add(row);
                    }
                }

                // Begin renaming!
                foreach (DataGridViewRow row in rows)
                {
                    // Keys:
                    // 0 = FullPath
                    // 1 = Song Key
                    // 2 = BPM
                    // 3 = Collection
                    // --- [snip]
                }