gistfile1.txt

using System;
using System.IO;
using System.Reflection;
using Excel = Microsoft.Office.Interop.Excel;

namespace CSV2XLS
{
    class CSV2XLS
    {
        public struct ColumnProperties
        {
            public string NumberFormat { get; set; }
            public float ColumnWidth { get; set; }
        }

        public static bool ConvertToXLS(string csv, string filename, ColumnProperties[] columnProperties = null)
        {
            var path = Path.GetDirectoryName(filename);

            if (File.Exists(filename) || !HasWriteAccessToDirectory(path)) {
                return false;
            }

            try
            {
                var xlApp = new Excel.Application();
                var xlWorkbook = xlApp.Workbooks.Add(Missing.Value);
                var xlWorksheet = (Excel.Worksheet)xlWorkbook.Worksheets.get_Item(1);

                var lines = csv.Split(new string[] { "\r\n" }, StringSplitOptions.RemoveEmptyEntries);
                for (var y = 0; y < lines.Length; y++)
                {
                    var cells = lines[y].Split(',');

                    for (var x = 0; x < cells.Length; x++)
                    {
                        Excel.Range cell = (Excel.Range)xlWorksheet.Cells[y+1, x+1];
                        cell.Value = cells[x];

                        if (columnProperties != null)
                        {
                            if (columnProperties[x].ColumnWidth != null)
                            {
                                cell.ColumnWidth = columnProperties[x].ColumnWidth;
                            }

                            if (columnProperties[x].NumberFormat != null)
                            {
                                cell.NumberFormat = columnProperties[x].NumberFormat;
                            }
                        }
                    }
                }
           
                xlWorkbook.SaveAs(filename, Excel.XlFileFormat.xlWorkbookNormal, Missing.Value, Missing.Value,
                    Missing.Value, Missing.Value, Excel.XlSaveAsAccessMode.xlExclusive,
                    Missing.Value, Missing.Value, Missing.Value, Missing.Value, Missing.Value);

                xlWorkbook.Close(true, Missing.Value, Missing.Value);
                xlApp.Quit();

                ReleaseObject(xlWorksheet);
                ReleaseObject(xlWorkbook);
                ReleaseObject(xlApp);
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                return false;
            }

            return true;
        }

        private static bool HasWriteAccessToDirectory(string path)
        {
            try
            {
                // Attempt to get a list of security permissions from the folder. 
                // This will raise an exception if the path is read only or do not have access to view the permissions. 
                System.Security.AccessControl.DirectorySecurity ds = Directory.GetAccessControl(path);
                return true;
            }
            catch (UnauthorizedAccessException)
            {
                return false;
            }
        }

        private static void ReleaseObject(object obj)
        {
            try
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
                obj = null;
            }
            catch (Exception)
            {
                obj = null;
            }
            finally
            {
                GC.Collect();
            }
        }
    }
}