Export all data in DataGridView to local excel

When the method is called, the parameter can be written into its own DataGridView name

 #region DataGridView Export to local Excel file method
        public void DownloadDataGridView(DataGridView dgv)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog
            {
                Filter = "Execl files (*.xls)|*.xls",
                FilterIndex = 0,
                RestoreDirectory = true,
                CreatePrompt = true,
                Title = "Exported Excel"
            };
            saveFileDialog.ShowDialog();
            if (saveFileDialog.FileName == "")
            {
                return;
            }//end if
            Stream myStream = saveFileDialog.OpenFile();
            //use the default encode
            StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding(-0));
            string str = "";
            try
            {
                for (int i = 0; i < dgv.ColumnCount; i++)
                {
                    str += dgv.Columns[i].HeaderText;
                    str += "\t";
                }//end for
                sw.WriteLine(str);
                for (int j = 0; j < dgv.Rows.Count - 1; j++)
                {
                    string strTemp = "";
                    for (int k = 0; k < dgv.Columns.Count; k++)
                    {
                        object obj = dgv.Rows[j].Cells[k].Value;
                        if (obj != null)
                        {
                            strTemp += dgv.Rows[j].Cells[k].Value.ToString();
                        }//end if
                        else
                        {
                            strTemp = "";
                        }//end else
                        strTemp += "\t";
                    }//end for k
                    sw.WriteLine(strTemp);
                }//end for j
                sw.Close();
                myStream.Close();
                MessageBox.Show("Success to Export the Excel File：\n" + saveFileDialog.FileName);
            }//end try
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }//end catch
            finally
            {
                sw.Close();
                myStream.Close();
            }//end finally
        }
        #endregion