在窗体中把DataGridView中的数据导出Excel

  //DataGridView导出Excel
         private void bt_Excl_Click(object sender, EventArgs e)
         {
             SaveFileDialog saveFileDialog = new SaveFileDialog();

             saveFileDialog.Filter = "Microsoft Excel 工作表 (.xls)|*.xls";
             saveFileDialog.FilterIndex = ;
             saveFileDialog.RestoreDirectory = true;
             saveFileDialog.CreatePrompt = true;
             saveFileDialog.Title = "导出Excel文件到";
             DateTime now = DateTime.Now;
             saveFileDialog.FileName = now.Year.ToString().PadLeft() + now.Month.ToString().PadLeft(, '') + now.Day.ToString().PadLeft(, '') + "-" + now.Hour.ToString().PadLeft(, '') + now.Minute.ToString().PadLeft(, '') + now.Second.ToString().PadLeft(, '');
             saveFileDialog.ShowDialog();
             Stream myStream;
             myStream = saveFileDialog.OpenFile();
             StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding("gb2312"));
             string str = "";
             try
             {
                 //写标题
                 for (int i = ; i < dataTitl.ColumnCount; i++)
                 {
                     if (i > )
                     {
                         str += "\t";
                     }
                     str += dataTitl.Columns[i].HeaderText;
                 }
                 sw.WriteLine(str);
                 //写内容
                 for (int j = ; j < dataTitl.Rows.Count; j++)
                 {
                     string tempStr = "";
                     for (int k = ; k < dataTitl.Columns.Count; k++)
                     {
                         if (k > )
                         {
                             tempStr += "\t";
                         }
                         tempStr += dataTitl.Rows[j].Cells[k].Value.ToString();
                     }
                     sw.WriteLine(tempStr);
                 }
                 sw.Close();
                 myStream.Close();
             }
             catch (Exception)
             {
                 MessageBox.Show("题目导出完成。", "导出", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
             }
             finally
             {
                 sw.Close();
                 myStream.Close();
             }
         }