private void buttonToExcel_Click(object sender, EventArgs e)
{
     SaveFileDialog saveFileDialog = new SaveFileDialog();
     saveFileDialog.Filter = "Execl files (*.xls)|*.xls";
     saveFileDialog.FilterIndex = 0;
     saveFileDialog.RestoreDirectory = true;
     saveFileDialog.CreatePrompt = true;
     saveFileDialog.Title = "Export Excel File To";
     saveFileDialog.ShowDialog();
     Stream myStream;
     myStream = saveFileDialog.OpenFile();
     StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding(-0));
     string str = "";
     try
     {
         //写标题
         for (int i = 0; i < this.dataGridView3.ColumnCount; i++)
         {
             if (i > 0)
             {
                 str += "\t";
             }
             str += this.dataGridView3.Columns[i].HeaderText;
         }
         sw.WriteLine(str);
         //写内容
         for (int j = 0; j < this.dataGridView3.Rows.Count; j++)
         {
             string tempStr = "";
             for (int k = 0; k < this.dataGridView3.Columns.Count; k++)
             {
                 if (k > 0)
                 {
                     tempStr += "\t";
                 }
                 tempStr += this.dataGridView3.Rows[j].Cells[k].Value + "";
             }
             sw.WriteLine(tempStr);
         }
         sw.Close();
         myStream.Close();
     }
     catch (Exception ex)
     {
         MessageBox.Show(ex.ToString());
     }
     finally
     {
         sw.Close();
         myStream.Close();
     }      
     MessageBox.Show("OK");
}