Copy the entire contents of a directory in C#


Question

I want to copy the entire contents of a directory from one location to another in C#.

There doesn't appear to be a way to do this using System.IO classes without lots of recursion.

There is a method in VB that we can use if we add a reference to Microsoft.VisualBasic:

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

This seems like a rather ugly hack. Is there a better way?

1
488
7/16/2018 7:30:18 AM

Accepted Answer

Much easier

//Now Create all of the directories
foreach (string dirPath in Directory.GetDirectories(SourcePath, "*", 
    SearchOption.AllDirectories))
    Directory.CreateDirectory(dirPath.Replace(SourcePath, DestinationPath));

//Copy all the files & Replaces any files with the same name
foreach (string newPath in Directory.GetFiles(SourcePath, "*.*", 
    SearchOption.AllDirectories))
    File.Copy(newPath, newPath.Replace(SourcePath, DestinationPath), true);
515
3/7/2014 7:48:49 PM

Hmm, I think I misunderstand the question but I'm going to risk it. What's wrong with the following straightforward method?

public 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));
}

EDIT Since this posting has garnered an impressive number of downvotes for such a simple answer to an equally simple question, let me add an explanation. Please read this before downvoting.

First of all, this code is not intendend as a drop-in replacement to the code in the question. It is for illustration purpose only.

Microsoft.VisualBasic.Devices.Computer.FileSystem.CopyDirectory does some additional correctness tests (e.g. whether the source and target are valid directories, whether the source is a parent of the target etc.) that are missing from this answer. That code is probably also more optimized.

That said, the code works well. It has (almost identically) been used in a mature software for years. Apart from the inherent fickleness present with all IO handlings (e.g. what happens if the user manually unplugs the USB drive while your code is writing to it?), there are no known problems.

In particular, I’d like to point out that the use of recursion here is absolutely not a problem. Neither in theory (conceptually, it’s the most elegant solution) nor in practice: this code will not overflow the stack. The stack is large enough to handle even deeply nested file hierarchies. Long before stack space becomes a problem, the folder path length limitation kicks in.

Notice that a malicious user might be able to break this assumption by using deeply-nested directories of one letter each. I haven’t tried this. But just to illustrate the point: in order to make this code overflow on a typical computer, the directories would have to be nested a few thousand times. This is simply not a realistic scenario.


Licensed under: CC-BY-SA with attribution
Not affiliated with: Stack Overflow
Icon