Populate ComboBox with Each FileType From Directory

Question

Basically, I have a ComboBox which I want to populate with File Extensions from a specific Directory .

Currently, I'm using:

Dim dir = "C:\"
For Each file As String In System.IO.Directory.GetFiles(dir)
   cmb_FileTypes.Items.Add(System.IO.Path.GetExtension(file))
Next

This doesn't work properly because it basically loads all the extensions for all the files in the directory. I want it so that it shows each ONE file type. for instance, if there are 10 files:

• File1.jpg
• File2.jpg
• File3.png
• File4.mp3
• File5.mp3
• File6.dat
• File7.dat
• File8.tif
• File9.jpg
• File10.mp3

Out of these 10 Files, there are 6 file extensions that are different file extensions:

• Jpg
• Png
• Mp3
• Dat
• tif

How do I load each 1 one these file extensions into the ComboBox rather than just repeating it?

Answer 1

使用LINQ在一个批量中添加组合框的所有扩展。

cmb_FileTypes.Items.AddRange((From name In Directory.GetFiles(dir) Select Path.GetExtension(name).Replace(".", "") Distinct).ToArray())

Answer 2

You could use LINQ to group the extensions

For Each file As String In Directory.GetFiles(dir).[Select](Function(p) Path.GetExtension(p)).Distinct().OrderBy(Function(p) p).ToList()
    cmb_FileTypes.Items.Add(System.IO.Path.GetExtension(file))
Next

or you can create a method which returns a List<string> containing unique extensions.

Public Function UniqueExtensions(filenames As String()) As List(Of String)
    Dim extSet As New HashSet(Of String)(StringComparer.OrdinalIgnoreCase)
    For Each file As String In filenames
        extSet.Add(System.IO.Path.GetExtension(file))
    Next
    Return extSet.ToList()
End Function