Imports System.Collections
Imports System.Collections.Generic
Imports System.IO

Module Module1

    Sub Main()
        Try
            ' Get a list of the files to use for the sorted set.
            Dim files1 As IEnumerable = _
                Directory.EnumerateFiles("\\archives\2007\media", "*", _
                                                          SearchOption.AllDirectories)
            ' Create a sorted set using the ByFileExtension comparer.
            Dim mediaFiles1 As SortedSet(Of String) = _
                New SortedSet(Of String)(New ByFileExtension)

            ' Note that there is a SortedSet constructor that takes an IEnumerable,
            ' but to remove the path information they must be added individually.
            For Each f As String In files1
                mediaFiles1.Add(f.Substring((f.LastIndexOf("\") + 1)))
            Next

            ' Remove elements that have non-media extensions. See the 'isDoc' method.
            Console.WriteLine("Remove docs from the set...")
            Console.WriteLine(vbTab & "Count before: {0}", mediaFiles1.Count.ToString)
            mediaFiles1.RemoveWhere(AddressOf isDoc)
            Console.WriteLine(vbTab & "Count after: {0}", mediaFiles1.Count.ToString)

            Console.WriteLine()

            ' List all the avi files.
            Dim aviFiles As SortedSet(Of String) = mediaFiles1.GetViewBetween("avi", "avj")
            Console.WriteLine("AVI files:")
            For Each avi As String In aviFiles
                Console.WriteLine(vbTab & "{0}", avi)
            Next

            Console.WriteLine()

            ' Create another sorted set.
            Dim files2 As IEnumerable = _
                Directory.EnumerateFiles("\\archives\2008\media", "*", _
                                      SearchOption.AllDirectories)
            Dim mediaFiles2 As SortedSet(Of String) = _
                New SortedSet(Of String)(New ByFileExtension)
            For Each f As String In files2
                mediaFiles2.Add(f.Substring((f.LastIndexOf("\") + 1)))
            Next

            ' Remove elements in mediaFiles1 that are also in mediaFiles2.
            Console.WriteLine("Remove duplicates (of mediaFiles2) from the set...")
            Console.WriteLine(vbTab & "Count before: {0}", _
                    mediaFiles1.Count.ToString)
            mediaFiles1.ExceptWith(mediaFiles2)
            Console.WriteLine(vbTab & "Count after: {0}", _
                    mediaFiles1.Count.ToString)

            Console.WriteLine()

            Console.WriteLine("List of mediaFiles1:")
            For Each f As String In mediaFiles1
                Console.WriteLine(vbTab & "{0}", f)
            Next

            ' Create a set of the sets.
            Dim comparer As IEqualityComparer(Of SortedSet(Of String)) = _
                SortedSet(Of String).CreateSetComparer()
            Dim allMedia As HashSet(Of SortedSet(Of String)) = _
                    New HashSet(Of SortedSet(Of String))(comparer)
            allMedia.Add(mediaFiles1)
            allMedia.Add(mediaFiles2)

        Catch ioEx As IOException
            Console.WriteLine(ioEx.Message)
        Catch AuthEx As UnauthorizedAccessException
            Console.WriteLine(AuthEx.Message)
        End Try


    End Sub

    ' Defines a predicate deligate to use
    ' for the SortedSet.RemoveWhere method.
    Private Function isDoc(ByVal s As String) As Boolean
        If (s.ToLower.EndsWith(".txt") _
                    OrElse (s.ToLower.EndsWith(".doc") _
                    OrElse (s.ToLower.EndsWith(".xls") _
                    OrElse (s.ToLower.EndsWith(".xlsx") _
                    OrElse (s.ToLower.EndsWith(".pdf") _
                    OrElse (s.ToLower.EndsWith(".doc") _
                    OrElse s.ToLower.EndsWith(".docx"))))))) Then
            Return True
        Else
            Return False
        End If
    End Function

    ' Defines a comparer to create a sorted set
    ' that is sorted by the file extensions.
    Public Class ByFileExtension
        Implements IComparer(Of String)
        Dim xExt, yExt As String

        Dim caseiComp As CaseInsensitiveComparer = _
                            New CaseInsensitiveComparer
        Public Function Compare(ByVal x As String, ByVal y As String) _
                                                                As Integer
            ' Parse the extension from the file name. 
            xExt = x.Substring(x.LastIndexOf(".") + 1)
            yExt = y.Substring(y.LastIndexOf(".") + 1)

            ' Compare the file extensions. 
            Dim vExt As Integer = caseiComp.Compare(xExt, yExt)
            If vExt <> 0 Then
                Return vExt
            Else
                ' The extension is the same, 
                ' so compare the filenames. 
                Return caseiComp.Compare(x, y)
            End If
        End Function        

    End Class
End Module

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;


class Program
{
    static void Main(string[] args)
    {
        try
        {
            // Get a list of the files to use for the sorted set.
            IEnumerable<string> files1 =
                Directory.EnumerateFiles(@"\\archives\2007\media",
                "*", SearchOption.AllDirectories);

            // Create a sorted set using the ByFileExtension comparer.
            SortedSet<string> mediaFiles1 =
                new SortedSet<string>(new ByFileExtension());

            // Note that there is a SortedSet constructor that takes an IEnumerable,
            // but to remove the path information they must be added individually.
            foreach (string f in files1)
            {
                mediaFiles1.Add(f.Substring(f.LastIndexOf(@"\") + 1));
            }

            // Remove elements that have non-media extensions.
            // See the 'isDoc' method.
            Console.WriteLine("Remove docs from the set...");
            Console.WriteLine("\tCount before: {0}", mediaFiles1.Count.ToString());
            mediaFiles1.RemoveWhere(isDoc);
            Console.WriteLine("\tCount after: {0}", mediaFiles1.Count.ToString());


            Console.WriteLine();

            // List all the avi files.
            SortedSet<string> aviFiles = mediaFiles1.GetViewBetween("avi", "avj");

            Console.WriteLine("AVI files:");
            foreach (string avi in aviFiles)
            {
                Console.WriteLine("\t{0}", avi);
            }

            Console.WriteLine();

            // Create another sorted set.
            IEnumerable<string> files2 =
                Directory.EnumerateFiles(@"\\archives\2008\media",
                    "*", SearchOption.AllDirectories);

            SortedSet<string> mediaFiles2 = new SortedSet<string>(new ByFileExtension());

            foreach (string f in files2)
            {
                mediaFiles2.Add(f.Substring(f.LastIndexOf(@"\") + 1));
            }

            // Remove elements in mediaFiles1 that are also in mediaFiles2.
            Console.WriteLine("Remove duplicates (of mediaFiles2) from the set...");
            Console.WriteLine("\tCount before: {0}", mediaFiles1.Count.ToString());
            mediaFiles1.ExceptWith(mediaFiles2);
            Console.WriteLine("\tCount after: {0}", mediaFiles1.Count.ToString());

            Console.WriteLine();

            Console.WriteLine("List of mediaFiles1:");
            foreach (string f in mediaFiles1)
            {
                Console.WriteLine("\t{0}",f);
            }

            // Create a set of the sets.
            IEqualityComparer<SortedSet<string>> comparer =
                SortedSet<string>.CreateSetComparer();

            HashSet<SortedSet<string>> allMedia =
                new HashSet<SortedSet<string>>(comparer);
            allMedia.Add(mediaFiles1);
            allMedia.Add(mediaFiles2);
        }
        catch(IOException ioEx)
        {
            Console.WriteLine(ioEx.Message);
        }

        catch (UnauthorizedAccessException AuthEx)
        {
            Console.WriteLine(AuthEx.Message);

        }
    }

    // Defines a predicate delegate to use
    // for the SortedSet.RemoveWhere method.
    private static bool isDoc(string s)
    {
        if (s.ToLower().EndsWith(".txt") ||
            s.ToLower().EndsWith(".doc") ||
            s.ToLower().EndsWith(".xls") ||
            s.ToLower().EndsWith(".xlsx") ||
            s.ToLower().EndsWith(".pdf") ||
            s.ToLower().EndsWith(".doc") ||
            s.ToLower().EndsWith(".docx"))
        {
            return true;
        }
        else
        {
            return false;
        }
    }


}

// Defines a comparer to create a sorted set
// that is sorted by the file extensions.
public class ByFileExtension : IComparer<string>
{
    string xExt, yExt;

    CaseInsensitiveComparer caseiComp = new CaseInsensitiveComparer();

    public int Compare(string x, string y)
    {
        // Parse the extension from the file name. 
        xExt = x.Substring(x.LastIndexOf(".") + 1);
        yExt = y.Substring(y.LastIndexOf(".") + 1);

        // Compare the file extensions. 
        int vExt = caseiComp.Compare(xExt, yExt);
        if (vExt != 0)
        {
            return vExt;
        }
        else
        {
            // The extension is the same, 
            // so compare the filenames. 
            return caseiComp.Compare(x, y);
        }
    }
}