GetFiles with multiple extensions

Question

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

How do you filter on more than one extension?

I've tried:

FileInfo[] Files = dinfo.GetFiles("*.jpg;*.tiff;*.bmp");
FileInfo[] Files = dinfo.GetFiles("*.jpg,*.tiff,*.bmp");

Solution 1

Why not create an extension method? That's more readable.

public static IEnumerable<FileInfo> GetFilesByExtensions(this DirectoryInfo dir, params string[] extensions)
{
    if (extensions == null) 
         throw new ArgumentNullException("extensions");
    IEnumerable<FileInfo> files = Enumerable.Empty<FileInfo>();
    foreach(string ext in extensions)
    {
       files = files.Concat(dir.GetFiles(ext));
    }
    return files;
}

EDIT: a more efficient version:

public static IEnumerable<FileInfo> GetFilesByExtensions(this DirectoryInfo dir, params string[] extensions)
{
    if (extensions == null) 
         throw new ArgumentNullException("extensions");
    IEnumerable<FileInfo> files = dir.EnumerateFiles();
    return files.Where(f => extensions.Contains(f.Extension));
}

Usage:

DirectoryInfo dInfo = new DirectoryInfo(@"c:\MyDir");
dInfo.GetFilesByExtensions(".jpg",".exe",".gif");

Solution 2

You can get every file, then filter the array:

public static IEnumerable<FileInfo> GetFilesByExtensions(this DirectoryInfo dirInfo, params string[] extensions)
{
    var allowedExtensions = new HashSet<string>(extensions, StringComparer.OrdinalIgnoreCase);

    return dirInfo.EnumerateFiles()
                  .Where(f => allowedExtensions.Contains(f.Extension));
}

This will be (marginally) faster than every other answer here.
In .Net 3.5, replace EnumerateFiles with GetFiles (which is slower).

And use it like this:

var files = new DirectoryInfo(...).GetFilesByExtensions(".jpg", ".mov", ".gif", ".mp4");

Solution 3

You can't do that, because GetFiles only accepts a single search pattern. Instead, you can call GetFiles with no pattern, and filter the results in code:

string[] extensions = new[] { ".jpg", ".tiff", ".bmp" };

FileInfo[] files =
    dinfo.GetFiles()
         .Where(f => extensions.Contains(f.Extension.ToLower()))
         .ToArray();

If you're working with .NET 4, you can use the EnumerateFiles method to avoid loading all FileInfo objects in memory at once:

string[] extensions = new[] { ".jpg", ".tiff", ".bmp" };

FileInfo[] files =
    dinfo.EnumerateFiles()
         .Where(f => extensions.Contains(f.Extension.ToLower()))
         .ToArray();

Solution 4

You can use LINQ Union method:

dir.GetFiles("*.txt").Union(dir.GetFiles("*.jpg")).ToArray();

Solution 5

The following retrieves the jpg, tiff and bmp files and gives you an IEnumerable<FileInfo> over which you can iterate:

var files = dinfo.GetFiles("*.jpg")
    .Concat(dinfo.GetFiles("*.tiff"))
    .Concat(dinfo.GetFiles("*.bmp"));

If you really need an array, simply stick .ToArray() at the end of this.

View more solutions

Comments

[Thomas Levesque]

I guess you mean "more than one extension"... it doesn't work with two either

[rd42]

yeup doesn't work for two either

[John Saunders]

BTW, are you aware that GetFiles is not related to C#, but only related to .NET?

[Vikram]

@JohnSaunders, are you sure about this?

[John Saunders]

@VikramNarkar: yes. You won't find it in the C# Reference, and it works equally well from VB.NET or any other CLR language.

[Vikram]

@JohnSaunders, Thanks a lot!

[Thomas Levesque]

That will be very inefficient if there are many files in the directory...

[rd42]

Thanks, I used the .NET 4 and got the following error. I'm new to this, so apologies is this is an obvious fix: Error 4 'bool' does not contain a definition for 'ToArray' and no extension method 'ToArray' accepting a first argument of type 'bool' could be found (are you missing a using directive or an assembly reference?)

[Thomas Levesque]

A closing bracket was missing, I fixed it

[Thomas Levesque]

You don't need to create a separate instance of DirectoryInfo for each type... and there is a lot of repeated code, you should refactor that with a method. Anyway, I updated my answer to fix the error, did you try it ?

[Cheng Chen]

Exactly.EnumerateFiles() is better at performance.

[SLaks]

This is inefficient.

[SLaks]

It would be faster to use a HashSet<string>.

[Thomas Levesque]

@SLaks, perhaps, depending on the number of extensions... For only 3 extensions I don't think the difference is significant.

[Cheng Chen]

@Slaks: emm..it's better if I get all the files first and then filter it with different extensions.

[SLaks]

Yes. See my answer. Also, you ought to call SelectMany instead of Concat: return extensions.SelectMany(dir.GetFiles);

[Jeff Winn]

Rather than checking the extension as shown above, you can use the first example and pass the search pattern into EnumerateFiles and still be able to use checks against the filename rather than only being able to inspect the extension while retaining the efficiency of the 2nd example.

[Doc Snuggles]

To avoid missing Capital Written Extensions I would add a StringComparer.OrdinalIgnoreCase to the Contains-Method. return files.Where(f => extensions.Contains(f.Extension, StringComparer.OrdinalIgnoreCase));

[Wessam El Mahdy]

Worked for me, thanks.

[Jeff]

@DocSnuggles +1 per C# Interactive window> new[] { ".jpg", ".exe", ".gif" }.Contains(".GIF") false and > new[] { ".jpg", ".exe", ".gif" }.Contains(".GIF", StringComparer.OrdinalIgnoreCase) true

[Developer63]

Fantastic solution, worked perfectly for me. I like that it's one line of code, the line is very readable and clear in its intent, I know what it's doing and why at a glance.

[Oleksii Zhyglov]

it is better to return array FilesInfo[], not collection, cause original method also returns n array:

[Oleksii Zhyglov]

static class ExtensionMethods { public static FileInfo[] GetFilesByExtensions(this DirectoryInfo dir, params string[] extensions) { if (extensions == null) throw new ArgumentNullException("extensions"); IEnumerable<FileInfo> files = dir.EnumerateFiles(); return files.Where(f => extensions.Contains(f.Extension)).ToArray(); } }

[Dominic Isaia]

I like this solution best because it's simple and easy to read.

[Sid133]

For me, having a single .xlsx file in the dir folder, the result is coming up as 2 .xlsx file with same name

[Ievgen]

@Sid133 how it can be? Union is performed on the different extensions.

[Sid133]

@Ievgen No idea, i have posted problem statement here. stackoverflow.com/q/72041497/9304804