Using control in functions C#

public static void Sync(string sourcePath, string destinationPath)
       {
           bool dirExisted = DirExists(destinationPath);

           //get the source files
           string[] srcFiles = Directory.GetFiles(sourcePath);

           foreach (string sourceFile in srcFiles)
           {
               FileInfo sourceInfo = new FileInfo(sourceFile);
               string destFile = Path.Combine(destinationPath, sourceInfo.Name);

               if (!dirExisted && File.Exists(destFile))
               {
                   FileInfo destInfo = new FileInfo(destFile);
                   if (sourceInfo.LastWriteTime > destInfo.LastWriteTime)
                   {
                       //file is newer, so copy it
                       File.Copy(sourceFile, Path.Combine(destinationPath, sourceInfo.Name), true);

                      MessageBox.Show(sourceFile + "copied(newer version)");




                   }
               }

               else
               {
                   File.Copy(sourceFile,Path.Combine(destinationPath,sourceInfo.Name));
                   MessageBox.Show(sourceFile + "copied");
               }
           }

           DeleteOldDestinationFiles(srcFiles, destinationPath);

           //now process the directories if exist
           string[] dirs = Directory.GetDirectories(sourcePath);

           foreach (string dir in dirs)
           {
               DirectoryInfo dirInfo = new DirectoryInfo(dir);

               //recursive do the directories
               Sync(dir, Path.Combine(destinationPath, dirInfo.Name));
           }
       }