Some time ago, I wrote this post  with this accompanying source code. It showed the way to use NTFS file structures to enumerate files and show the files that take more space in your hard disk. Then a user posted a note asking if it would be possible to know if, instead of knowing the files, I could show the directories that consume more space, and I said “of course, you can do it with some minor changes!”, and showed him a sample of the code.

Then I realized that that could be an interesting way to improve the program and show a little bit about working with the data we have – gather the data is important, but work with it to extract every bit of information is even more! So, let’s go to it (if you haven’t already read the original article, do it now).

Working with the data

The original code to retrieve all the files size using the NTFS file structures is:

var ntfsReader =
    new NtfsReader(driveToAnalyze, RetrieveMode.All);
nodes =
        .Where(n => (n.Attributes &
                     (Attributes.Hidden | Attributes.System |
                      Attributes.Temporary | Attributes.Device |
                      Attributes.Directory | Attributes.Offline |
                      Attributes.ReparsePoint | Attributes.SparseFile)) == 0)
        .OrderByDescending(n => n.Size).ToList();

The reader will get all nodes from the selected drive, will filter them, removing the hidden, system, temporary and directories and will sort it by descending order. The ordering will not be necessary for our needs, because we want the directories sizes.

Before working with the data, let’s create a new WPF project that will show our data in a list. In Visual Studio (you should open Visual Studio in elevated mode, because to use the NTFS structures you must have admin rights), create a new WPF project (.NET Framework) and add the dll NTFSReader from this site as a reference to the project. Then, add this code in MainWindow.xaml for our UI:

<Window x:Class="NtfsDirectories.MainWindow"
        Title="MainWindow" Height="450" Width="800">
            <RowDefinition Height="40"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="30"/>
        <StackPanel Orientation="Horizontal" Margin="5">
            <TextBlock Text="Drive" VerticalAlignment="Center"/>
            <ComboBox x:Name="DrvCombo" Margin="5,0" Width="100" 
        <StackPanel Grid.Row="0" HorizontalAlignment="Right" Orientation="Horizontal" Margin="5">
            <TextBlock Text="Level" VerticalAlignment="Center"/>
            <ComboBox x:Name="LevelCombo" Margin="5,0" Width="100" 
                      VerticalContentAlignment="Center" SelectedIndex="3" 
        <ListBox x:Name="DirectoriesList" Grid.Row="1" 
                 VirtualizingPanel.IsVirtualizingWhenGrouping="True" >
                    <StackPanel Orientation="Horizontal">
                        <TextBlock Text="{Binding Name}" 
                                   Margin="5,0" Width="450"/>
                        <TextBlock Text="{Binding Size,StringFormat=N0}" 
                                   Margin="5,0" Width="150" TextAlignment="Right"/>
        <TextBlock x:Name="StatusTxt" Grid.Row="2" HorizontalAlignment="Center" Margin="5"/>

That will add two comboboxes, to select the drive and level to drill down and a listbox to show the results. Then, we should add the code to get the drives in the constructor of MainWindow:

public MainWindow()
    var ntfsDrives = DriveInfo.GetDrives()
        .Where(d => d.DriveFormat == "NTFS").ToList();
    DrvCombo.ItemsSource = ntfsDrives;
    DrvCombo.SelectionChanged += DrvCombo_SelectionChanged;

This code will fill the drives combo with all the NTFS drives in the system. When the user changes the selection, the drive will be scanned and will get all files:

private IEnumerable<INode> nodes = null;
private async void DrvCombo_SelectionChanged(object sender, SelectionChangedEventArgs e)
    if (DrvCombo.SelectedItem == null) return;
    var driveToAnalyze = (DriveInfo)DrvCombo.SelectedItem;
    DrvCombo.IsEnabled = false;
    LevelCombo.IsEnabled = false;
    StatusTxt.Text = "Analyzing drive";
    await Task.Factory.StartNew(() => { nodes = GetFileNodes(driveToAnalyze); });

    LevelCombo.SelectedIndex = -1;
    LevelCombo.SelectedIndex = 3;

    DrvCombo.IsEnabled = true;
    LevelCombo.IsEnabled = true;
    StatusTxt.Text = "";

You will notice the fact that I’m setting the LevelCombo’s SelectedIndex to -1 then to 3.I do that to achieve two things: clean the directories list when the drive changes and trigger the change event for the level combo. The GetFileNodes method will scan the drive and will return a list of files in that drive:

private static IEnumerable<INode> GetFileNodes(DriveInfo driveToAnalyze)
    var ntfsReader =
        new NtfsReader(driveToAnalyze, RetrieveMode.All);
            .Where(n => (n.Attributes &
                         (Attributes.Hidden | Attributes.System |
                          Attributes.Temporary | Attributes.Device |
                          Attributes.Directory | Attributes.Offline |
                          Attributes.ReparsePoint | Attributes.SparseFile)) == 0);

Now, we must get the directories sizes depending on the level the user selected and add them to the listbox. This is done when the level changes in the combobox:

private void LevelCombo_OnSelectionChanged(object sender, SelectionChangedEventArgs e)
    if (DirectoriesList == null)
    int level = Int32.MaxValue-1;
    if (LevelCombo.SelectedIndex < 0 || nodes == null)
        DirectoriesList.ItemsSource = null;
    else if (LevelCombo.SelectedIndex < 3)
        level = LevelCombo.SelectedIndex;
    DirectoriesList.ItemsSource = GetDirectorySizes(nodes, level+1);

As you can see, when the level is negative, I clean the results list, and when there is a level set, I call the GetDirectoriesSizes method. If the user selects the Max level, I set the level to Int32.MaxValue. The GetDirectoriesSizes method is:

private IList<DirectorySize> GetDirectorySizes(IEnumerable<INode> nodes, int level)
     var directories = nodes
        .Select(n => new
            Path = string.Join(Path.DirectorySeparatorChar.ToString(),
            Node = n
        .GroupBy(g => g.Path)
        .Select(g => new DirectorySize(g.Key, g.Sum(d => (Int64)d.Node.Size)))
        .OrderByDescending(d => d.Size)
      return directories;

In this case, I use LINQ to group the files in the desired level. The first Select will break the path into its parts, then will take the parts only to the level we want and rejoin the parts. This will allow us to group the files according to the wanted level. One gotcha is that, when we select level 3, for example, we will want to show all files grouped to the level 3, but we will also want those that are on the upper levels. For example, for the level 3, we will want to show the files in C:\, C:\Temp, C:\Program Files\Windows and so on. If the file is under a path more than 3 levels down, it will be grouped with the upper directory.

When you run this project, you will have something like this:


As you can see, once we have the data, we can work on it and obtain different views. One thing that helps a lot in C# is the use of LINQ, which allows to transform the data in a simple way. The function that we used can be extended to any level you want and will bring the good results.

All the source code for this project is in

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