Question

I’m working on a project and I need to list all subdirectories in a directory. For example, how could I list all the subdirectories in drive C:?

Answer 1

Use Directory.GetDirectories to get the subdirectories of the directory specified by “your_directory_path”. The result is an array of strings.

var directories = Directory.GetDirectories("your_directory_path");

By default, that only returns subdirectories one level deep. There are options to return all recursively and to filter the results, documented here, and shown in Clive’s answer.

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Avoiding an UnauthorizedAccessException

It’s easily possible that you’ll get an UnauthorizedAccessException if you hit a directory to which you don’t have access.

You may have to create your own method that handles the exception, like this:

public class CustomSearcher
{ 
    public static List<string> GetDirectories(string path, string searchPattern = "*",
        SearchOption searchOption = SearchOption.AllDirectories)
    {
        if (searchOption == SearchOption.TopDirectoryOnly)
            return Directory.GetDirectories(path, searchPattern).ToList();

        var directories = new List<string>(GetDirectories(path, searchPattern));

        for (var i = 0; i < directories.Count; i++)
            directories.AddRange(GetDirectories(directories[i], searchPattern));

        return directories;
    }

    private static List<string> GetDirectories(string path, string searchPattern)
    {
        try
        {
            return Directory.GetDirectories(path, searchPattern).ToList();
        }
        catch (UnauthorizedAccessException)
        {
            return new List<string>();
        }
    }
}

And then call it like this:

var directories = CustomSearcher.GetDirectories("your_directory_path");

This traverses a directory and all its subdirectories recursively. If it hits a subdirectory that it cannot access, something that would’ve thrown an UnauthorizedAccessException, it catches the exception and just returns an empty list for that inaccessible directory. Then it continues on to the next subdirectory.