select random file from directory

Question

I've seen a few examples but none so far in C#, what is the best way to select a random file under a directory?

In this particular case I want to select a wallpaper from "C:\wallpapers" every 15 or so minutes.

Thanks.

Solution 1

select random file from directory

private string getrandomfile2(string path)
    {
        string file = null;
        if (!string.IsNullOrEmpty(path))
        {
            var extensions = new string[] { ".png", ".jpg", ".gif" };
            try
            {
                var di = new DirectoryInfo(path);
                var rgFiles = di.GetFiles("*.*").Where( f => extensions.Contains( f.Extension.ToLower()));
                Random R = new Random();
                file = rgFiles.ElementAt(R.Next(0,rgFiles.Count())).FullName;
            }
            // probably should only catch specific exceptions
            // throwable by the above methods.
            catch {}
        }
        return file;
    }

Solution 2

Get all files in an array and then retrieve one randomly

var rand = new Random();
var files = Directory.GetFiles("c:\\wallpapers","*.jpg");
return files[rand.Next(files.Length)];

Solution 3

If you're doing this for wallpapers, you don't want to just select a file at random because it won't appear random to the user.

What if you pick the same one three times in a row? Or alternate between two?

That's "random," but users don't like it.

See this post about how to display random pictures in a way users will like.

Solution 4

var files = new DirectoryInfo(@"C:\dev").GetFiles();
int index = new Random().Next(0, files.Length);

Console.WriteLine(files[index].Name);

Solution 5

why not just:

1. get the files into an array
2. use the Random class to select a number that is random between 0 and files.Length
3. Grab the file from the array using the random number as the index

View more solutions

Comments

[Rich]

When shuffling you should probably also account for the case that a file gets deleted or added to the directory (in which case you need to re-shuffle).

[discoverAnkit]

I tried this code snippet and its working fine but it is only searching in the folder wallpapers and not searching any sub-folders inside wallpapers. How to modify the code to do that as well?

[Mouk]

Consider passing SearchOption.AllDirectories as a third argument to the GetFiles method.

[Guffa]

Catching exceptions and silently ignoring them is bad. You should either handle the exception and return something useful, or not catch them at all.