C# 导出Excel（csv ）

 private void DataGridViewToExcel(DataGridView dataGridView1)
        {
            SaveFileDialog dlg = new SaveFileDialog();
            dlg.Filter = "Execl files (*.xls)|*.xls";
            dlg.FilterIndex = 0;
            dlg.RestoreDirectory = true;
            dlg.CreatePrompt = true;
            dlg.Title = "保存为Excel文件";

            if (dlg.ShowDialog() == DialogResult.OK)
            {
                Stream myStream;
                myStream = dlg.OpenFile();
                StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding(-0));
                string columnTitle = "";
                try
                {
                    //写入列标题   
                    for (int i = 0; i < dataGridView1.ColumnCount; i++)
                    {
                        if (i > 0)
                        {
                            columnTitle += "\t";
                        }
                        columnTitle += dataGridView1.Columns[i].HeaderText;
                    }
                    sw.WriteLine(columnTitle);

                    //写入列内容   
                    for (int j = 0; j < dataGridView1.Rows.Count; j++)
                    {
                        string columnValue = "";
                        for (int k = 0; k < dataGridView1.Columns.Count; k++)
                        {
                            if (k > 0)
                            {
                                columnValue += "\t";
                            }
                            if (dataGridView1.Rows[j].Cells[k].Value == null)
                                columnValue += "";
                            else
                                columnValue += dataGridView1.Rows[j].Cells[k].Value.ToString().Trim();
                        }
                        sw.WriteLine(columnValue);
                    }
                    sw.Close();
                    myStream.Close();
                    MessageBox.Show("导出成功！");
                }
                catch (Exception e)
                {
                    MessageBox.Show(e.ToString());
                }
                finally
                {
                    sw.Close();
                    myStream.Close();
                }
            }
        }