Can you call Directory.GetFiles() with multiple filters?

Question

I am trying to use the Directory.GetFiles() method to retrieve a list of files of multiple types, such as mp3\'s and jpg\'s. I have t

Answer 1

I had the same problem and couldn't find the right solution so I wrote a function called GetFiles:

/// <summary>
/// Get all files with a specific extension
/// </summary>
/// <param name="extensionsToCompare">string list of all the extensions</param>
/// <param name="Location">string of the location</param>
/// <returns>array of all the files with the specific extensions</returns>
public string[] GetFiles(List<string> extensionsToCompare, string Location)
{
    List<string> files = new List<string>();
    foreach (string file in Directory.GetFiles(Location))
    {
        if (extensionsToCompare.Contains(file.Substring(file.IndexOf('.')+1).ToLower())) files.Add(file);
    }
    files.Sort();
    return files.ToArray();
}

This function will call Directory.Getfiles() only one time.

For example call the function like this:

string[] images = GetFiles(new List<string>{"jpg", "png", "gif"}, "imageFolder");

EDIT: To get one file with multiple extensions use this one:

/// <summary>
    /// Get the file with a specific name and extension
    /// </summary>
    /// <param name="filename">the name of the file to find</param>
    /// <param name="extensionsToCompare">string list of all the extensions</param>
    /// <param name="Location">string of the location</param>
    /// <returns>file with the requested filename</returns>
    public string GetFile( string filename, List<string> extensionsToCompare, string Location)
    {
        foreach (string file in Directory.GetFiles(Location))
        {
            if (extensionsToCompare.Contains(file.Substring(file.IndexOf('.') + 1).ToLower()) &&& file.Substring(Location.Length + 1, (file.IndexOf('.') - (Location.Length + 1))).ToLower() == filename) 
                return file;
        }
        return "";
    }

For example call the function like this:

string image = GetFile("imagename", new List<string>{"jpg", "png", "gif"}, "imageFolder");

Answer 2

If you are using VB.NET (or imported the dependency into your C# project), there actually exists a convenience method that allows to filter for multiple extensions:

Microsoft.VisualBasic.FileIO.FileSystem.GetFiles("C:\\path", Microsoft.VisualBasic.FileIO.SearchOption.SearchAllSubDirectories, new string[] {"*.mp3", "*.jpg"});

In VB.NET this can be accessed through the My-namespace:

My.Computer.FileSystem.GetFiles("C:\path", FileIO.SearchOption.SearchAllSubDirectories, {"*.mp3", "*.jpg"})

Unfortunately, these convenience methods don't support a lazily evaluated variant like Directory.EnumerateFiles() does.

Answer 3

for

var exts = new[] { "mp3", "jpg" };

You could:

public IEnumerable<string> FilterFiles(string path, params string[] exts) {
    return
        Directory
        .EnumerateFiles(path, "*.*")
        .Where(file => exts.Any(x => file.EndsWith(x, StringComparison.OrdinalIgnoreCase)));
}

• Don't forget the new .NET4 Directory.EnumerateFiles for a performance boost (What is the difference between Directory.EnumerateFiles vs Directory.GetFiles?)
• "IgnoreCase" should be faster than "ToLower" (.EndsWith("aspx", StringComparison.OrdinalIgnoreCase) rather than .ToLower().EndsWith("aspx"))

But the real benefit of EnumerateFiles shows up when you split up the filters and merge the results:

public IEnumerable<string> FilterFiles(string path, params string[] exts) {
    return 
        exts.Select(x => "*." + x) // turn into globs
        .SelectMany(x => 
            Directory.EnumerateFiles(path, x)
            );
}

It gets a bit faster if you don't have to turn them into globs (i.e. exts = new[] {"*.mp3", "*.jpg"} already).

Performance evaluation based on the following LinqPad test (note: Perf just repeats the delegate 10000 times) https://gist.github.com/zaus/7454021

( reposted and extended from 'duplicate' since that question specifically requested no LINQ: Multiple file-extensions searchPattern for System.IO.Directory.GetFiles )

Answer 4

in .NET 2.0 (no Linq):

public static List<string> GetFilez(string path, System.IO.SearchOption opt,  params string[] patterns)
{
    List<string> filez = new List<string>();
    foreach (string pattern in patterns)
    {
        filez.AddRange(
            System.IO.Directory.GetFiles(path, pattern, opt)
        );
    }


    // filez.Sort(); // Optional
    return filez; // Optional: .ToArray()
}

Then use it:

foreach (string fn in GetFilez(path
                             , System.IO.SearchOption.AllDirectories
                             , "*.xml", "*.xml.rels", "*.rels"))
{}

Answer 5

There is also a descent solution which seems not to have any memory or performance overhead and be quite elegant:

string[] filters = new[]{"*.jpg", "*.png", "*.gif"};
string[] filePaths = filters.SelectMany(f => Directory.GetFiles(basePath, f)).ToArray();

Answer 6

The following function searches on multiple patterns, separated by commas. You can also specify an exclusion, eg: "!web.config" will search for all files and exclude "web.config". Patterns can be mixed.

private string[] FindFiles(string directory, string filters, SearchOption searchOption)
{
    if (!Directory.Exists(directory)) return new string[] { };

    var include = (from filter in filters.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries) where !string.IsNullOrEmpty(filter.Trim()) select filter.Trim());
    var exclude = (from filter in include where filter.Contains(@"!") select filter);

    include = include.Except(exclude);

    if (include.Count() == 0) include = new string[] { "*" };

    var rxfilters = from filter in exclude select string.Format("^{0}$", filter.Replace("!", "").Replace(".", @"\.").Replace("*", ".*").Replace("?", "."));
    Regex regex = new Regex(string.Join("|", rxfilters.ToArray()));

    List<Thread> workers = new List<Thread>();
    List<string> files = new List<string>();

    foreach (string filter in include)
    {
        Thread worker = new Thread(
            new ThreadStart(
                delegate
                {
                    string[] allfiles = Directory.GetFiles(directory, filter, searchOption);
                    if (exclude.Count() > 0)
                    {
                        lock (files)
                            files.AddRange(allfiles.Where(p => !regex.Match(p).Success));
                    }
                    else
                    {
                        lock (files)
                            files.AddRange(allfiles);
                    }
                }
            ));

        workers.Add(worker);

        worker.Start();
    }

    foreach (Thread worker in workers)
    {
        worker.Join();
    }

    return files.ToArray();

}

Usage:

foreach (string file in FindFiles(@"D:\628.2.11", @"!*.config, !*.js", SearchOption.AllDirectories))
            {
                Console.WriteLine(file);
            }