Directory.EnumerateFiles 在多个扩展名的情况下不返回文件

Question

I have a problem which I cannot handle with.

When I use EnumerateFiles it returns no files, where I know there should be over 3k results.

My code looks like here:

private IEnumerable<string> TestGetFiles(string path, params string[] exts)
    {
        var extsAsWildcards = exts.Select(x => "*." + x).ToArray();
        return exts.Select(x => "*." + x) .SelectMany(x => Directory.EnumerateFiles(path, x));

    }

I took this code from here: Git link

None of solutions work and I need this solution for multiple extensions. The only method worked for me is this:

private IEnumerable<string> GetCurrentFontFiles(string item)
    {
        IEnumerable<string> files = Directory.EnumerateFiles(item + Path.DirectorySeparatorChar, "*.ttf", SearchOption.AllDirectories).ToArray();
        return files;
    }

Which works, but only for single extension.

Please help me guys, I dont want to use GetFiles which is extremly slow (I have over 10k files in folder).

EDIT1 I call method with this filter:

string[] extensions = {"png"};

EDIT2

My example to reproduce:

    private IEnumerable<string> TestGetFiles(string path, params string[] exts)
    {
        return exts.Select(x => "*." + x).SelectMany(x => Directory.EnumerateFiles(path, x));
    }
    private List<FileSizeList> GetPNGFiles(string pathForFiles)
    {
        List<FileSizeList> PNGFiles = new List<FileSizeList>();

        string[] extensions = {"png"};
        IEnumerable<string> files = TestGetFiles(pathForFiles, extensions);
        foreach (var file in files)
        { //no iteration here

        }
    }

EDIT3 Working solution

I know where was the problem. I modified a code and added missing SearchOption

private IEnumerable<string> TestGetFiles(string path, params string[] exts)
{
    var extensions = exts
       .Select(x => x.StartsWith(".") ? x : "." + x)
       .ToArray();
    return Directory.EnumerateFiles(path,"*.*",SearchOption.AllDirectories)
        .Where(fn => extensions.Contains(Path.GetExtension(fn), StringComparer.InvariantCultureIgnoreCase));
}

Answer 1

Your approach is slow because you are searching this folder that contains 10k files multiple times (for every extension). Instead you can use this:

private IEnumerable<string> TestGetFiles(string path, params string[] exts)
{
    var extensions  = exts
       .Select(x => x.StartsWith(".") ? x : "." + x)
       .ToArray();
    return Directory.EnumerateFiles(path ,SearchOption.AllDirectories)            
       . Where(fn => extensions.Contains(Path.GetExtension(fn), StringComparer.InvariantCultureIgnoreCase));
}

Obviously you also want to search subdirectories. Then use AllDirectories .

As MicroVirus has commented it was case-sensitive. Now it is case-insensitive. So it doesn't matter if the extension is png or PNG . Maybe that was causing your issue.