Today I had the task of copying a directory recursively in C#. The first thing I did was type into my project “Directory.” and see if intellisense brought up a function called Directory.Copy. Unfortunately there is not a Directory.Copy, which to me seems like an oversight, as copying a directory is fairly common. Maybe it is not an action commonly done in C#.

So next I went to my browser and did a search. Well, I am not the first, nor will I be the last to solve this. There are a number of solutions online and each seem to have both positive and negative comments.

Option 1 – A directory copy using recursion

Pros: This is simple and to the point and elegant.

Cons: One complaint is that this could cause a stack overly by using recursion but this might not be a valid con as the filesystem restrictions in Windows might prevent a stack overflow anyway.

Since I am dealing with a small controlled tree, the con will not affect me., but since we are dealing with a file system, this is likely not to occur.

        private static void CopyFilesRecursively(DirectoryInfo source, DirectoryInfo target)
        {
            foreach (DirectoryInfo dir in source.GetDirectories())
                CopyFilesRecursively(dir, target.CreateSubdirectory(dir.Name));
            foreach (FileInfo file in source.GetFiles())
                file.CopyTo(Path.Combine(target.FullName, file.Name));
        }

Option 2 – Use SearchOption.AllDirectories to create the directory structure then then copy all the files

Pros: Does not use recursion
Cons: Are there any?

        private static void CopyFilesRecursively(String SourcePath, String DestinationPath)
        {
            // First create all of the directories
            foreach (string dirPath in Directory.GetDirectories(SourcePath, "*", SearchOption.AllDirectories))
                Directory.CreateDirectory(dirPath.Replace(SourcePath, DestinationPath));

            // Copy all the files
            foreach (string newPath in Directory.GetFiles(SourcePath, "*.*", SearchOption.AllDirectories))
                File.Copy(newPath, newPath.Replace(SourcePath, DestinationPath));
        }

Option 3 – Use one of the methods recommended by MSDN

Unfortunately MSDN is not consistent, and recommends two different methods in two different places, which I am sure were written by different teams.

using System;
using System.IO;

class DirectoryCopyExample
{
    static void Main()
    {
        DirectoryCopy(".", @".\temp", true);
    }

    private static void DirectoryCopy(
        string sourceDirName, string destDirName, bool copySubDirs)
    {
      DirectoryInfo dir = new DirectoryInfo(sourceDirName);
      DirectoryInfo[] dirs = dir.GetDirectories();

      // If the source directory does not exist, throw an exception.
        if (!dir.Exists)
        {
            throw new DirectoryNotFoundException(
                "Source directory does not exist or could not be found: "
                + sourceDirName);
        }

        // If the destination directory does not exist, create it.
        if (!Directory.Exists(destDirName))
        {
            Directory.CreateDirectory(destDirName);
        }

        // Get the file contents of the directory to copy.
        FileInfo[] files = dir.GetFiles();

        foreach (FileInfo file in files)
        {
            // Create the path to the new copy of the file.
            string temppath = Path.Combine(destDirName, file.Name);

            // Copy the file.
            file.CopyTo(temppath, false);
        }

        // If copySubDirs is true, copy the subdirectories.
        if (copySubDirs)
        {

            foreach (DirectoryInfo subdir in dirs)
            {
                // Create the subdirectory.
                string temppath = Path.Combine(destDirName, subdir.Name);

                // Copy the subdirectories.
                DirectoryCopy(subdir.FullName, temppath, copySubDirs);
            }
        }
    }
}

Or the different one they posted here:

using System;
using System.IO;

class CopyDir
{
    public static void CopyAll(DirectoryInfo source, DirectoryInfo target)
    {
        if (source.FullName.ToLower() == target.FullName.ToLower())
        {
            return;
        }

        // 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())
        {
            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);
        }
    }

    public static void Main()
    {
        string sourceDirectory = @"c:\sourceDirectory";
        string targetDirectory = @"c:\targetDirectory";

        DirectoryInfo diSource = new DirectoryInfo(sourceDirectory);
        DirectoryInfo diTarget = new DirectoryInfo(targetDirectory);

        CopyAll(diSource, diTarget);
    }

    // Output will vary based on the contents of the source directory.
}

Option 4 – Use Microsoft.VisualBasic

Pros: One line.
Cons: You have to reference an additional dll that you otherwise do not need.
This additional dll is not available in Mono for cross-platform development.

new Microsoft.VisualBasic.Devices.Computer().
    FileSystem.CopyDirectory( sourceFolder, outputFolder );

There are various other methods:

Resources:
http://stackoverflow.com/questions/58744/best-way-to-copy-the-entire-contents-of-a-directory-in-c
http://msdn.microsoft.com/en-us/library/system.io.directoryinfo.aspx
http://msdn.microsoft.com/en-us/library/bb762914.aspx
http://xneuron.wordpress.com/2007/04/12/copy-directory-and-its-content-to-another-directory-in-c/
http://www.logiclabz.com/c/copy-directory-in-net-c-including-sub-folders.aspx