GetExtensionsInFolder with C#

program.cs

var pathSelected = "D:\\TORRENTS";

DirectoryInfo directorySelected = new DirectoryInfo(pathSelected);

var filesInfo = directorySelected.GetFiles("*", SearchOption.AllDirectories).ToList();

List<string> extensions = new List<string>();

foreach (var file in filesInfo)
{
    if (!extensions.Contains(file.Extension))
    {
        extensions.Add(file.Extension);
        Console.WriteLine(file.Extension);
    }
}

Console.ReadLine();