Sort a List(Of IO.FileInfo) by file-extension

Question

I have a directory with files with these filenames:

12.mp4
34.wmv
56.ogm
78.avi
90.m4v

In my application I list the files of the directory into a List(Of File.Info) which is indexed as default:

FileList.Item(0).Name = 12.mp4
FileList.Item(1).Name = 34.wmv
FileList.Item(2).Name = 56.ogm
FileList.Item(3).Name = 78.avi
FileList.Item(4).Name = 90.m4v

But I need to process the files by the file-extension sorted in ascending mode, so this is the Item-indexation I need:

FileList.Item(0).Name = 78.avi
FileList.Item(1).Name = 90.m4v
FileList.Item(2).Name = 12.mp4
FileList.Item(3).Name = 56.ogm
FileList.Item(4).Name = 34.wmv

How I can sort the List like that in VB.NET or C#?

Answer 1

var sorted = FileList.OrderBy(f => f.Extension);

Answer 2

If this is a List(Of FileInfo ) , you could use:

FileList.Sort(Function(fi1,fi2) return fi1.Extension.CompareTo(fi2.Extension))

Note that a LINQ solution would potentially be nicer if you can do this sort when you build your FileInfo list, ie:

Dim FileList = theDirectoryInfo.GetFiles().OrderBy(Function(f) f.Extension).ToList()

However, if the list already is built, sorting in place will potentially be cleaner than using LINQ to rebuild the list then reassign.

Answer 3

Try this:

public class ExtComparer : IComparer<string>
{
    public int Compare(string x, string y)
    {
        //return Path.GetExtension(x).CompareTo(Path.GetExtension(y)); or
        return System.String.Compare(Path.GetExtension(x), Path.GetExtension(y), System.StringComparison.Ordinal);
    }
}

Use: MyList.Sort(new ExtComparer ());