c# 导出Excel 怎么设置格式！
导出代码为！！
        public bool SaveToExcel(System.Data.DataTable table, string fileName)
        {
            if (table.Rows.Count == 0)
            {
                return false;
            }

            Microsoft.Office.Interop.Excel.Application excel = new ApplicationClass();
            int rowindex = 1;
            int colindex = 0;
            Workbook work = excel.Workbooks.Add(true); ;
            foreach (DataColumn col in table.Columns)
            {
                colindex++;
                excel.Cells[1, colindex] = col.ColumnName;
            }
            foreach (DataRow row in table.Rows)
            {
                rowindex++;
                colindex = 0;
                foreach (DataColumn col in table.Columns)
                {
                    colindex++;
                    excel.Cells[rowindex, colindex] = row[col.ColumnName].ToString();
                }
            }
            excel.Visible = false;
            excel.ActiveWorkbook.SaveAs(fileName, XlFileFormat.xlExcel8, null, null, false, false, XlSaveAsAccessMode.xlNoChange, null, null, null, null, null);
            excel.Quit();
            excel = null;
            GC.Collect();
            MessageBox.Show("已保存!");
            return true;
        }


求助怎么设置格式