public void EsportaDataTable(System.Data.DataTable tab, string pathFile, bool WriteColumnName, bool soloColonneConCaption)
        {
            try
            {
                //Avvio una istanza di Excel
                Microsoft.Office.Interop.Excel.Application exc = new Microsoft.Office.Interop.Excel.Application();
                try
                {
                    Microsoft.Office.Interop.Excel.Workbooks workbooks = exc.Workbooks;

                    Microsoft.Office.Interop.Excel._Workbook workbook = workbooks.Add(XlWBATemplate.xlWBATWorksheet);
                    Microsoft.Office.Interop.Excel._Worksheet worksheet = (_Worksheet)workbook.Worksheets[1];

                    worksheet.Name = "Foglio1";

                    int startRow = 1;
                    int cntCol = 1;
                    string colName = "";

                    if (WriteColumnName)
                    {
                        cntCol = 1;
                        for (int c = 0; c < tab.Columns.Count; c++)
                        {
                            if (soloColonneConCaption)
                            {
                                if (!Convert.ToString("" + tab.Columns[c].Caption).Equals(""))
                                {
                                    colName = Utility.ConvertColumnToChar(cntCol) + startRow.ToString();

                                    Microsoft.Office.Interop.Excel.Range range = worksheet.get_Range(colName, System.Reflection.Missing.Value);
                                    Object[] data = new Object[] { tab.Columns[c].Caption.Trim().ToUpper() };
                                    range.GetType().InvokeMember("Value", System.Reflection.BindingFlags.SetProperty, null, range, data);

                                    cntCol++;
                                }
                            }
                            else
                            {
                                colName = Utility.ConvertColumnToChar(cntCol) + startRow.ToString();

                                Microsoft.Office.Interop.Excel.Range range = worksheet.get_Range(colName, System.Reflection.Missing.Value);
                                Object[] data = new Object[] { tab.Columns[c].Caption.Trim().ToUpper() };
                                range.GetType().InvokeMember("Value", System.Reflection.BindingFlags.SetProperty, null, range, data);

                                cntCol++;
                            }
                        }
                        startRow++;
                    }

                    foreach (DataRow riga in tab.Rows)
                    {
                        cntCol = 1;
                        for (int c = 0; c < tab.Columns.Count; c++)
                        {
                            if (soloColonneConCaption)
                            {
                                if (!Convert.ToString("" + tab.Columns[c].Caption).Equals(""))
                                {
                                    colName = Utility.ConvertColumnToChar(cntCol) + startRow.ToString();

                                    Microsoft.Office.Interop.Excel.Range range = worksheet.get_Range(colName, System.Reflection.Missing.Value);
                                    Object[] data = new Object[] { riga[c] };
                                    range.GetType().InvokeMember("Value", System.Reflection.BindingFlags.SetProperty, null, range, data);

                                    cntCol++;
                                }
                            }
                            else
                            {
                                colName = Utility.ConvertColumnToChar(cntCol) + startRow.ToString();

                                Microsoft.Office.Interop.Excel.Range range = worksheet.get_Range(colName, System.Reflection.Missing.Value);
                                Object[] data = new Object[] { riga[c] };
                                range.GetType().InvokeMember("Value", System.Reflection.BindingFlags.SetProperty, null, range, data);

                                cntCol++;
                            }
                        }
                        startRow++;
                       
                    }

                    workbook.Close(true, pathFile, null);
                }
                catch (Exception)
                {
                }
                finally
                {
                    exc.Quit();
                }
              
            }
            catch (Exception ex)
            {
            }
        }



 public class Utility
    {
        public static string ConvertColumnToChar(int numCol)
        {
            string res = "-";
            try
            {
                if (numCol <= 26)
                {
                    switch (numCol)
                    {
                        case 0:
                            res = "-";
                            break;
                        case 1:
                            res = "A";
                            break;
                        case 2:
                            res = "B";
                            break;
                        case 3:
                            res = "C";
                            break;
                        case 4:
                            res = "D";
                            break;
                        case 5:
                            res = "E";
                            break;
                        case 6:
                            res = "F";
                            break;
                        case 7:
                            res = "G";
                            break;
                        case 8:
                            res = "H";
                            break;
                        case 9:
                            res = "I";
                            break;
                        case 10:
                            res = "J";
                            break;
                        case 11:
                            res = "K";
                            break;
                        case 12:
                            res = "L";
                            break;
                        case 13:
                            res = "M";
                            break;
                        case 14:
                            res = "N";
                            break;
                        case 15:
                            res = "O";
                            break;
                        case 16:
                            res = "P";
                            break;
                        case 17:
                            res = "Q";
                            break;
                        case 18:
                            res = "R";
                            break;
                        case 19:
                            res = "S";
                            break;
                        case 20:
                            res = "T";
                            break;
                        case 21:
                            res = "U";
                            break;
                        case 22:
                            res = "V";
                            break;
                        case 23:
                            res = "W";
                            break;
                        case 24:
                            res = "X";
                            break;
                        case 25:
                            res = "Y";
                            break;
                        case 26:
                            res = "Z";
                            break;
                        default:
                            break;
                    }
                }
                else
                {
                    int Param1 = Convert.ToInt32(numCol / 26);
                    int Param2 = numCol - 26;

                    res = ConvertColumnToChar(Param1) + ConvertColumnToChar(Param2);
                }
            }
            catch (Exception)
            {
            }
            return res;
        }
    }