Convert WordDocument to PDF using C-Sharp

// Create a new Microsoft Word application object
               MSWord.Application word = new MSWord.Application();

               // C# doesn't have optional arguments so we'll need a dummy value
               object oMissing = System.Reflection.Missing.Value;

               // Get list of Word files in specified directory
               DirectoryInfo dirInfo = new DirectoryInfo(path);
               FileInfo[] wordFiles = dirInfo.GetFiles(@"D:\HtmlFolder\Sample.doc");

               word.Visible = false;
               word.ScreenUpdating = false;

               foreach (FileInfo wordFile in wordFiles)
               {
                   // Cast as Object for word Open method
                   Object filename = (Object)wordFile.FullName;

                   // Use the dummy value as a placeholder for optional arguments
                   MSWord.Document doc = word.Documents.Open(ref filename, ref oMissing,
                       ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                       ref oMissing, ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                       ref oMissing, ref oMissing, ref oMissing, ref oMissing);
                   doc.Activate();

                   object outputFileName = wordFile.FullName.Replace(".doc", ".pdf");
                   object fileFormat = MSWord.WdSaveFormat.wdFormatPDF;

                   // Save document into PDF Format
                   doc.SaveAs(ref outputFileName,
                       ref fileFormat, ref oMissing, ref oMissing,
                       ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                       ref oMissing, ref oMissing, ref oMissing, ref oMissing,
                       ref oMissing, ref oMissing, ref oMissing, ref oMissing);

                   // Close the Word document, but leave the Word application open.
                   // doc has to be cast to type _Document so that it will find the
                   // correct Close method.              
                   object saveChanges = MSWord.WdSaveOptions.wdDoNotSaveChanges;
                   ((MSWord._Document)doc).Close(ref saveChanges, ref oMissing, ref oMissing);
                   doc = null;
               }

               // word has to be cast to type _Application so that it will find
               // the correct Quit method.
               ((MSWord._Application)word).Quit(ref oMissing, ref oMissing, ref oMissing);
               word = null;