Count of files in C# with LINQ

Question

Env: C#, VStudio 2013, 4.5 Framework, Winforms

Goal : Getting the number of files (Count) in a folder and subfolder that match extensions stored in an array of string. The array of extension can be with the "." of not. {".dat","txt",".msg"}

What i've done so far : When I'm having the "." in the array of extensions, everything is working : {".dat",".txt",".msg"}

I have tried the Replace but it's always returning 0.

The working code (Only if always with the "." in array of string):

string[] ext= new string[] { ".txt", ".msg", ".dat" };
totalFilesInTN = Directory.EnumerateFiles(dlg1.SelectedPath, "*.*", SearchOption.AllDirectories)
                          .Count(s => ext.Any(s1 => s1 == Path.GetExtension(s)));

The not working code (always return 0) :

string[] ext= new string[] { "txt", ".msg", "dat" };
totalFilesInTN = Directory.EnumerateFiles(dlg1.SelectedPath, "*.*", SearchOption.AllDirectories)
                          .Count(s => ext.Any(s1 => s1 == Path.GetExtension(s).Replace(".", "")));

Answer 1

The documentation for the Path.GetExtension method states that the return value is:

The extension of the specified path (including the period "."), or null, or String.Empty.

Your second block of code strips off the '.' so none of the elements will match. Therefore, go the opposite way with your list of extensions and just ensure that the start of each extension has a '.' and then use your first block of code.

string[] ext = new string[] {"txt", ".msg", ".dat" }
    .Select(x => x.StartsWith(".") ? x : "." + x)
    .ToArray();

Answer 2

You need to replace the . dot in both the array ext element and the directory item. You need to use .Replace with s1 as well to compare the array and file extension after removing dot from each.

string[] ext= new string[] { "txt", ".msg", "dat" };
totalFilesInTN = Directory.EnumerateFiles(dlg1.SelectedPath, "*.*", SearchOption.AllDirectories)
                 .Count(s => ext.Any(s1 => s1.Replace(".", "") == Path.GetExtension(s).Replace(".", "")));