how to copy a directory in c#

how to copy a directory it contains .pdf files in c#

 protected void Button1_Click(object sender, EventArgs e)
        {
            string sourceDirectory = @"D:\pdf";
            string targetDirectory = @"D:\CopyFolderNew123";

            Copy(sourceDirectory, targetDirectory);
        }

        public static void Copy(string sourceDirectory, string targetDirectory)
        {
            DirectoryInfo diSource = new DirectoryInfo(sourceDirectory);
            DirectoryInfo diTarget = new DirectoryInfo(targetDirectory);

            CopyAll(diSource, diTarget);
        }

        public static void CopyAll(DirectoryInfo source, DirectoryInfo target)
        {
           // string sourceDirectory = @"D:\pdf";
         
            // Check if the target directory exists, if not, create it.
            if (Directory.Exists(target.FullName) == false)
            {
                Directory.CreateDirectory(target.FullName);
            }


          
            // Copy each file into it's new directory.
            foreach (FileInfo fi in source.GetFiles())
            {
                if (fi.Extension.ToUpper() == ".PDF")
                {
                    Console.WriteLine(@"Copying {0}\{1}", target.FullName, fi.Name);
                    fi.CopyTo(Path.Combine(target.ToString(), fi.Name), true);
                }
               
            }

            // Copy each subdirectory using recursion.
            foreach (DirectoryInfo diSourceSubDir in source.GetDirectories())
            {

                DirectoryInfo nextTargetSubDir =target.CreateSubdirectory(diSourceSubDir.Name);
                CopyAll(diSourceSubDir, nextTargetSubDir);
              
            }

          
        }