Import data in DataGridView to Csv file and export to Excel in C#

 public static bool dataGridViewToCSV(DataGridView dataGridView)
        {
            if (dataGridView.Rows.Count == 0)
            {
                MessageBox.Show("没有数据可导出!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                return false;
            }
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            saveFileDialog.Filter = "CSV files (*.csv)|*.csv";
            saveFileDialog.FilterIndex = 0;
            saveFileDialog.RestoreDirectory = true;
            saveFileDialog.CreatePrompt = true;
            saveFileDialog.FileName = null;
            saveFileDialog.Title = "保存";
            if (saveFileDialog.ShowDialog() == DialogResult.OK)
            {
                Stream stream = saveFileDialog.OpenFile();
                StreamWriter sw = new StreamWriter(stream, System.Text.Encoding.GetEncoding(-0));
                string strLine = "";
                try
                {
                    //表头
                    for (int i = 0; i < dataGridView.ColumnCount; i++)
                    {
                        if (i > 0)
                            strLine += ",";
                        strLine += dataGridView.Columns[i].HeaderText;
                    }
                    strLine.Remove(strLine.Length - 1);
                    sw.WriteLine(strLine);
                    strLine = "";
                    //表的内容
                    for (int j = 0; j < dataGridView.Rows.Count; j++)
                    {
                        strLine = "";
                        int colCount = dataGridView.Columns.Count;
                        for (int k = 0; k < colCount; k++)
                        {
                            if (k > 0 && k < colCount)
                                strLine += ",";
                            if (dataGridView.Rows[j].Cells[k].Value == null)
                                strLine += "";
                            else
                            {
                                string cell = dataGridView.Rows[j].Cells[k].Value.ToString().Trim();
                                //防止里面含有特殊符号
                                cell = cell.Replace("\"", "\"\"");
                                cell = "\"" + cell + "\"";
                                strLine += cell;
                            }
                        }
                        sw.WriteLine(strLine);
                    }
                    sw.Close();
                    stream.Close();
                    MessageBox.Show("数据被导出到：" + saveFileDialog.FileName.ToString(), "导出完毕", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message, "导出错误", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    return false;
                }
            }
            return true;
        }

public static bool dataGridViewToExcel(DataGridView dataGridView)
        {
            if (dataGridView.Rows.Count == 0)
            {
                MessageBox.Show("没有数据可导出!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                return false;
            }
            string fileName = "";
            string saveFileName = "";
            SaveFileDialog saveDialog = new SaveFileDialog();
            saveDialog.DefaultExt = "xlsx";
            saveDialog.Filter = "Excel文件|*.xlsx";
            saveDialog.FileName = fileName;
            saveDialog.ShowDialog();
            saveFileName = saveDialog.FileName;
            if (saveFileName.IndexOf(":") < 0)
                return false; //被点了取消
            Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();
            if (xlApp == null)
            {
                MessageBox.Show("无法创建Excel对象，您的电脑可能未安装Excel");
                return false;
            }
            Microsoft.Office.Interop.Excel.Workbooks workbooks = xlApp.Workbooks;
            Microsoft.Office.Interop.Excel.Workbook workbook =
                        workbooks.Add(Microsoft.Office.Interop.Excel.XlWBATemplate.xlWBATWorksheet);
            Microsoft.Office.Interop.Excel.Worksheet worksheet =
                        (Microsoft.Office.Interop.Excel.Worksheet)workbook.Worksheets[1];//取得sheet1 
                                                                                         //写入标题             
            for (int i = 0; i < dataGridView.ColumnCount; i++)
            { worksheet.Cells[1, i + 1] = dataGridView.Columns[i].HeaderText; }
            //写入数值
            for (int r = 0; r < dataGridView.Rows.Count; r++)
            {
                for (int i = 0; i < dataGridView.ColumnCount; i++)
                {
                    worksheet.Cells[r + 2, i + 1] = dataGridView.Rows[r].Cells[i].Value;
                }
                System.Windows.Forms.Application.DoEvents();
            }
            worksheet.Columns.EntireColumn.AutoFit();//列宽自适应
            MessageBox.Show(fileName + "资料保存成功", "提示", MessageBoxButtons.OK);
            if (saveFileName != "")
            {
                try
                {
                    workbook.Saved = true;
                    workbook.SaveCopyAs(saveFileName);  //fileSaved = true;                 
                }
                catch (Exception ex)
                {//fileSaved = false;                      
                    MessageBox.Show("导出文件时出错,文件可能正被打开！\n" + ex.Message);
                }
            }
            xlApp.Quit();
            Kill(xlApp);
            GC.Collect();//强行销毁      
            return true;
        }

//*********************************************************************************************//
        //*功能：当使用Excel.Application方法的时候，系统会自动创建一个Excel进程，即使当你使用Excel.Quit()之后，也是不会关闭的。        //*参数：通过进程ID来唯一标识我们自己创建的进程，然后在关闭Excel.Application的时候一同将进程Kill掉。        //*返回值：无        //*时间：2018-04-25        //**********************************************************************************************//        public static void Kill(Microsoft.Office.Interop.Excel.Application excel)        {            IntPtr t = new IntPtr(excel.Hwnd);            int k = 0;            GetWindowThreadProcessId(t, out k);            System.Diagnostics.Process p = System.Diagnostics.Process.GetProcessById(k);            p.Kill();        }