CSV to XLS utility (requires Microsoft.Office.Interop.Excel)

namespace CSVtoExcel

{

 using System;

 using Excel = Microsoft.Office.Interop.Excel;

 using File = System.IO.File;

 using Path = System.IO.Path;

 class Program

 {

   static void Main(string[] args)

   {

     if (args.Length == 0)

     {

       throw new ApplicationException("Missing file name");

     }

     string file = args[0];

     if (!File.Exists(file))

     {

       throw new System.IO.FileNotFoundException("File specified in command line not found", file);

     }

     var app = new Excel.Application() { DisplayAlerts = false };

     try

     {

       app.Workbooks.Open(file);

       app.ActiveWorkbook.SaveAs(

         Path.ChangeExtension(file, "xls"),

         FileFormat: Excel.XlFileFormat.xlWorkbookNormal,

         ConflictResolution: Excel.XlSaveConflictResolution.xlLocalSessionChanges);

     }

     finally

     {

       app.Quit();

     }

   }

 }

}