[c#] Multiple file-extensions searchPattern for System.IO.Directory.GetFiles

What is the syntax for setting multiple file-extensions as searchPattern on Directory.GetFiles()? For example filtering out files with .aspx and .ascx extensions.

// TODO: Set the string 'searchPattern' to only get files with
// the extension '.aspx' and '.ascx'.
var filteredFiles = Directory.GetFiles(path, searchPattern);

Update: LINQ is not an option, it has to be a searchPattern passed into GetFiles, as specified in the question.

look like this demo:

void Main()
{
    foreach(var f in GetFilesToProcess("c:\\", new[] {".xml", ".txt"}))
        Debug.WriteLine(f);
}
private static IEnumerable<string> GetFilesToProcess(string path, IEnumerable<string> extensions)
{
   return Directory.GetFiles(path, "*.*")
       .Where(f => extensions.Contains(Path.GetExtension(f).ToLower()));
}

Instead of the EndsWith function, I would choose to use the Path.GetExtension() method instead. Here is the full example:

var filteredFiles = Directory.EnumerateFiles( path )
.Where(
    file => Path.GetExtension(file).Equals( ".aspx", StringComparison.OrdinalIgnoreCase ) ||
            Path.GetExtension(file).Equals( ".ascx", StringComparison.OrdinalIgnoreCase ) );

or:

var filteredFiles = Directory.EnumerateFiles(path)
.Where(
    file => string.Equals( Path.GetExtension(file), ".aspx", StringComparison.OrdinalIgnoreCase ) ||
            string.Equals( Path.GetExtension(file), ".ascx", StringComparison.OrdinalIgnoreCase ) );

(Use StringComparison.OrdinalIgnoreCase if you care about performance: MSDN string comparisons)

GetFiles can only match a single pattern, but you can use Linq to invoke GetFiles with multiple patterns:

FileInfo[] fi = new string[]{"*.txt","*.doc"}
    .SelectMany(i => di.GetFiles(i, SearchOption.AllDirectories))
    .ToArray();

See comments section here: http://www.codeproject.com/KB/aspnet/NET_DirectoryInfo.aspx

Just would like to say that if you use FileIO.FileSystem.GetFiles instead of Directory.GetFiles, it will allow an array of wildcards.

For example:

Dim wildcards As String() = {"*.html", "*.zip"}
Dim ListFiles As List(Of String) = FileIO.FileSystem.GetFiles(directoryyouneed, FileIO.SearchOption.SearchTopLevelOnly, wildcards).ToList

I did a simple way for seach as many extensions as you need, and with no ToLower(), RegEx, foreach...

List<String> myExtensions = new List<String>() { ".aspx", ".ascx", ".cs" }; // You can add as many extensions as you want.
DirectoryInfo myFolder = new DirectoryInfo(@"C:\FolderFoo");
SearchOption option = SearchOption.TopDirectoryOnly; // Use SearchOption.AllDirectories for seach in all subfolders.
List<FileInfo> myFiles = myFolder.EnumerateFiles("*.*", option)
    .Where(file => myExtensions
    .Any(e => String.Compare(file.Extension, e, CultureInfo.CurrentCulture, CompareOptions.IgnoreCase) == 0))
    .ToList();

Working on .Net Standard 2.0.

var filteredFiles = Directory
    .EnumerateFiles(path, "*.*") // .NET4 better than `GetFiles`
    .Where(
        // ignorecase faster than tolower...
        file => file.ToLower().EndsWith("aspx")
        || file.EndsWith("ascx", StringComparison.OrdinalIgnoreCase))
    .ToList();

• 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"

Or, it may be faster to split and merge your globs (at least it looks cleaner):

"*.ext1;*.ext2".Split(';')
    .SelectMany(g => Directory.EnumerateFiles(path, g))
    .ToList();

var filteredFiles = Directory
    .GetFiles(path, "*.*")
    .Where(file => file.ToLower().EndsWith("aspx") || file.ToLower().EndsWith("ascx"))
    .ToList();

Edit 2014-07-23

You can do this in .NET 4.5 for a faster enumeration:

var filteredFiles = Directory
    .EnumerateFiles(path) //<--- .NET 4.5
    .Where(file => file.ToLower().EndsWith("aspx") || file.ToLower().EndsWith("ascx"))
    .ToList();

Directory.EnumerateFiles in MSDN

    /// <summary>
    /// Returns the names of files in a specified directories that match the specified patterns using LINQ
    /// </summary>
    /// <param name="srcDirs">The directories to seach</param>
    /// <param name="searchPatterns">the list of search patterns</param>
    /// <param name="searchOption"></param>
    /// <returns>The list of files that match the specified pattern</returns>
    public static string[] GetFilesUsingLINQ(string[] srcDirs,
         string[] searchPatterns,
         SearchOption searchOption = SearchOption.AllDirectories)
    {
        var r = from dir in srcDirs
                from searchPattern in searchPatterns
                from f in Directory.GetFiles(dir, searchPattern, searchOption)
                select f;

        return r.ToArray();
    }

var filtered = Directory.GetFiles(path)
    .Where(file => file.EndsWith("aspx", StringComparison.InvariantCultureIgnoreCase) || file.EndsWith("ascx", StringComparison.InvariantCultureIgnoreCase))
    .ToList();

The easy-to-remember, lazy and perhaps imperfect solution:

Directory.GetFiles(dir, "*.dll").Union(Directory.GetFiles(dir, "*.exe"))

I fear you will have to do somthing like this, I mutated the regex from here.

var searchPattern = new Regex(
    @"$(?<=\.(aspx|ascx))", 
    RegexOptions.IgnoreCase);
var files = Directory.EnumerateFiles(path)
    .Where(f => searchPattern.IsMatch(f))
    .ToList();

I would try to specify something like

var searchPattern = "as?x";

it should work.

c# version of @qfactor77's answer. This is the best way without LINQ .

string[] wildcards= {"*.mp4", "*.jpg"};
ReadOnlyCollection<string> filePathCollection = FileSystem.GetFiles(dirPath, Microsoft.VisualBasic.FileIO.SearchOption.SearchAllSubDirectories, wildcards);
string[] filePath=new string[filePathCollection.Count];
filePathCollection.CopyTo(filePath,0);

now return filePath string array. In the beginning you need

using Microsoft.VisualBasic.FileIO;
using System.Collections.ObjectModel;

also you need to add reference to Microsoft.VisualBasic

@Daniel B, thanks for the suggestion to write my own version of this function. It has the same behavior as Directory.GetFiles, but supports regex filtering.

string[] FindFiles(FolderBrowserDialog dialog, string pattern)
    {
        Regex regex = new Regex(pattern);

        List<string> files = new List<string>();
        var files=Directory.GetFiles(dialog.SelectedPath);
        for(int i = 0; i < files.Count(); i++)
        {
            bool found = regex.IsMatch(files[i]);
            if(found)
            {
                files.Add(files[i]);
            }
        }

        return files.ToArray();
    }

I found it useful, so I thought I'd share.

You can do it like this

new DirectoryInfo(path).GetFiles().Where(Current => Regex.IsMatch(Current.Extension, "\\.(aspx|ascx)", RegexOptions.IgnoreCase)

I like this method, because it is readable and avoids multiple iterations of the directory:

var allowedExtensions = new [] {".doc", ".docx", ".pdf", ".ppt", ".pptx", ".xls", ".xslx"}; 
var files = Directory
    .GetFiles(folder)
    .Where(file => allowedExtensions.Any(file.ToLower().EndsWith))
    .ToList();

I would use the following:

var ext = new string[] { ".ASPX", ".ASCX" };
FileInfo[] collection = (from fi in new DirectoryInfo(path).GetFiles()
                         where ext.Contains(fi.Extension.ToUpper())
                         select fi)
                         .ToArray();

EDIT: corrected due mismatch between Directory and DirectoryInfo

    public static bool CheckFiles(string pathA, string pathB)
    {
        string[] extantionFormat = new string[] { ".war", ".pkg" };
        return CheckFiles(pathA, pathB, extantionFormat);
    }
    public static bool CheckFiles(string pathA, string pathB, string[] extantionFormat)
    {
        System.IO.DirectoryInfo dir1 = new System.IO.DirectoryInfo(pathA);
        System.IO.DirectoryInfo dir2 = new System.IO.DirectoryInfo(pathB);
        // Take a snapshot of the file system. list1/2 will contain only WAR or PKG 
        // files
        // fileInfosA will contain all of files under path directories 
        FileInfo[] fileInfosA = dir1.GetFiles("*.*", 
                              System.IO.SearchOption.AllDirectories);
        // list will contain all of files that have ..extantion[]  
        // Run on all extantion in extantion array and compare them by lower case to 
        // the file item extantion ...
        List<System.IO.FileInfo> list1 = (from extItem in extantionFormat
                                          from fileItem in fileInfosA
                                          where extItem.ToLower().Equals 
                                          (fileItem.Extension.ToLower())
                                          select fileItem).ToList();
        // Take a snapshot of the file system. list1/2 will contain only WAR or  
        // PKG files
        // fileInfosA will contain all of files under path directories 
        FileInfo[] fileInfosB = dir2.GetFiles("*.*", 
                                       System.IO.SearchOption.AllDirectories);
        // list will contain all of files that have ..extantion[]  
        // Run on all extantion in extantion array and compare them by lower case to 
        // the file item extantion ...
        List<System.IO.FileInfo> list2 = (from extItem in extantionFormat
                                          from fileItem in fileInfosB
                                          where extItem.ToLower().Equals            
                                          (fileItem.Extension.ToLower())
                                          select fileItem).ToList();
        FileCompare myFileCompare = new FileCompare();
        // This query determines whether the two folders contain 
        // identical file lists, based on the custom file comparer 
        // that is defined in the FileCompare class. 
        return list1.SequenceEqual(list2, myFileCompare);
    }

A more efficient way of getting files with the extensions ".aspx" and ".ascx" that avoids querying the file system several times and avoids returning a lot of undesired files, is to pre-filter the files by using an approximate search pattern and to refine the result afterwards:

var filteredFiles = Directory.GetFiles(path, "*.as?x")
    .Select(f => f.ToLowerInvariant())
    .Where(f => f.EndsWith("px") || f.EndsWith("cx"))
    .ToList();