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{
                // Creating a Excel object. 
                Microsoft.Office.Interop.Excel._Application excel = new Microsoft.Office.Interop.Excel.Application();
                Microsoft.Office.Interop.Excel._Workbook workbook = excel.Workbooks.Add(Type.Missing);
                Microsoft.Office.Interop.Excel._Worksheet worksheet = null;

                try
                {

                    worksheet = workbook.ActiveSheet;

                    worksheet.Name = "ExportedFromDatGrid";

                    int cellRowIndex = 1;
                    int cellColumnIndex = 1;

                    //Loop through each row and read value from each column. 
                    for (int i = 0; i < dataGridView6.Rows.Count - 1; i++)
                    {
                        for (int j = 0; j < dataGridView6.Columns.Count; j++)
                        {
                            // Excel index starts from 1,1. As first Row would have the Column headers, adding a condition check. 
                            if (cellRowIndex == 1)
                            {
                                worksheet.Cells[cellRowIndex, cellColumnIndex] = dataGridView6.Columns[j].HeaderText;
                            }
                            else
                            {
                                worksheet.Cells[cellRowIndex, cellColumnIndex] = dataGridView6.Rows[i].Cells[j].Value.ToString();
                            }
                            cellColumnIndex++;
                        }
                        cellColumnIndex = 1;
                        cellRowIndex++;
                    }

                    //Getting the location and file name of the excel to save from user. 
                    SaveFileDialog saveDialog = new SaveFileDialog();
                    saveDialog.Filter = "Excel files (*.xlsx)|*.xlsx|All files (*.*)|*.*";
                    saveDialog.FilterIndex = 2;

                    if (saveDialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                    {
                        workbook.SaveAs(saveDialog.FileName);
                        MessageBox.Show("Export Successful");
                    }
                }
                catch (System.Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
                finally
                {
                    excel.Quit();
                    workbook = null;
                    excel = null;
                }

            }                    

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  for (int i = 0; i < dataGridView6.Rows.Count - 1; i++)  //Zeile
                    {

                        for (int j = 0; j < dataGridView6.Columns.Count; j++) //Spalte
                        {
                        //      MessageBox.Show(dataGridView6.Rows.Count.ToString());
                              MessageBox.Show(dataGridView6.Rows[i].Cells[j].Value.ToString());

        
                        if (String.IsNullOrEmpty(dataGridView6.Rows[i].Cells[j].Value.ToString()))
                        {
                            worksheet.Cells[cellRowIndex, cellColumnIndex] = " ";
                        }
                        else
                        {
                            worksheet.Cells[cellRowIndex, cellColumnIndex] = dataGridView6.Rows[i].Cells[j].Value.ToString();
                        }
                    
                            cellColumnIndex++;
                        }
                        cellColumnIndex = 1;
                        cellRowIndex++;
                    }                    

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worksheet.PageSetup.LeftMargin = Application.CentimetersToPoints(0.5);