linq to extract specific subset

Given a directory of files (as a FileInfo array) how would I go about extracting all the filenames that have a corresponding filename with a specific extension.

For example, given a directory of the following files;

file1.txt
file1.txt.xml
file2.txt
file2.txt.xml
file3.xml
file3.xml.x开发者_高级运维ml

How would I extract file1.txt, file2.txt and file3.xml. Basically, I am looking for any file that has a correspoding entry with my given extension (xml in this case).

Thanks in advance.

This code will produce a list of the corresponding files (assuming that files is an IEnumerable<FileInfo>:

var ext = ".xml"; // To match your example above
var list = files.Where(f => f.Extension.Equals(ext, StringComparison.OrdinalIgnoreCase))
                .Select( f => Path.Combine(f.DirectoryName, Path.GetFileNameWithoutExtension(f.Name)))
                .Where( n => File.Exists(n))
                .ToList();

James's solution works. You can also use

files.Where(fi => fi.Extension == ext).ToList();

You could go with something like

string path = @"C:\Temp\XYZ";
string mainExtension = ".txt"; // optionally use
string companionExtension = ".xml";

var mainFiles = Directory.GetFiles(path); // or (path, "*" + mainExtension); 
var companionFiles = Directory.GetFiles(path, "*" + companionExtension);

var filesWithCompanions = from file in mainFiles
                            from companion in companionFiles
                            where companion == file + companionExtension
                            select file;

If the directory is rather large, something like the below may be more optimal

var companionQuery = companionFiles.Select(file => file.Replace(Path.GetExtension(file), ""));
var companionSet = new HashSet<string>(companionQuery);
var filesWithCompanions = mainFiles.Where(companionSet.Contains);

var ext = ".xml";
FileInfo[] files = ...
var filered = files.Where(fi=> fi.Name.EndsWith(ext)).ToList();
// filtered is an List<FileInfo>

However, you probably don't need the ToList() (or the filters variable)

var ext = ".xml";
FileInfo[] files = ...
foreach(var file in files.Where(fi=> fi.Name.EndsWith(ext))
{ 
     // do something with "file" here
}