Can't get the name of directories sorted by name

Question

Hello experts,

I need to get the name of directories sorted by name, just like what is shown in the Windows explorer.

3 folders are in a path, Windows show them in the below order:

0_35_33

7_07_10

18_16_40

But Directory.GetDirectories and DirectoryInfo.GetDirectories both will return in the below order:

0_35_33

18_16_40

7_07_10

Note that the below lines will not help either:

.OrderByDescending(Function(p) p.Name).ToArray()

.OrderByDescending(Function(p) p.CreationTime).ToArray()

Please help :(

Answer 1

Hi @StewartBW ,

You can use a lambda expression or a custom sorting logic inline.

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim pathname As String = "testfolders"
        Dim directories As String() = Directory.GetDirectories(pathname)

        Array.Sort(directories, AddressOf CompareNaturally)

        For Each dir As String In directories
            Debug.WriteLine(Path.GetFileName(dir))
        Next
    End Sub

    Private Function CompareNaturally(x As String, y As String) As Integer
        Dim xName As String = Path.GetFileName(x)
        Dim yName As String = Path.GetFileName(y)
        Dim xParts As String() = Regex.Split(xName, "(\d+)")
        Dim yParts As String() = Regex.Split(yName, "(\d+)")

        For i As Integer = 0 To Math.Min(xParts.Length, yParts.Length) - 1
            If xParts(i) <> yParts(i) Then
                Dim xPart As Integer
                Dim yPart As Integer

                If Integer.TryParse(xParts(i), xPart) AndAlso Integer.TryParse(yParts(i), yPart) Then
                    Return xPart.CompareTo(yPart)
                Else
                    Return xParts(i).CompareTo(yParts(i))
                End If
            End If
        Next

        Return xParts.Length.CompareTo(yParts.Length)
    End Function

Best Regards.

Jiachen Li

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Answer 2

You can see this thread : https://learn.microsoft.com/en-us/answers/questions/608117/how-can-i-get-files-from-the-hard-disk-as-array-in

Answer 3

The following will sort properly.

using System.Text.RegularExpressions;

public static partial class Extensions
{
    public static IEnumerable<T> NaturalOrderBy<T>(this IEnumerable<T> items, Func<T, string> selector, StringComparer stringComparer = null)
    {
        var regex = new Regex(@"\d+", RegexOptions.Compiled);

        int maxDigits = items
            .SelectMany(value => regex.Matches(selector(value))
                .Select(digitChunk => (int?)digitChunk.Value.Length)).Max() ?? 0;

        return items.OrderBy(value => regex.Replace(selector(value), 
            match => match.Value.PadLeft(maxDigits, '0')), 
            stringComparer ?? StringComparer.CurrentCulture);
    }
}

Example which in this case uses file under a folder of the executable.

var fileNames = Directory.EnumerateFiles(Path.Combine(AppDomain.CurrentDomain.BaseDirectory,"Files"), "*.*", new EnumerationOptions
{
    IgnoreInaccessible = true
}).ToArray();

List<string> sorted = fileNames.NaturalOrderBy(x => x).ToList();
sorted.ForEach(x=> Console.WriteLine(Path.GetFileName(x)));