How do I get a directory size (files in the directory) in C#?

Question

I want to be able to get the size of one of the local directories using C#. I'm trying to avoid the following (pseudo like code), although in the worst case scenario I will have to settle for this:

    int GetSize(Directory)
    {
        int Size = 0;

        foreach ( File in Directory )
        {
            FileInfo fInfo of File;
            Size += fInfo.Size;
        }

        foreach ( SubDirectory in Directory )
        {
            Size += GetSize(SubDirectory);
        }
        return Size;
    }

Basically, is there a Walk() available somewhere so that I can walk through the directory tree? Which would save the recursion of going through each sub-directory.

Answer 1

A very succinct way to get a folder size in .net 4.0 is below. It still suffers from the limitation of having to traverse all files recursively, but it doesn't load a potentially huge array of filenames, and it's only two lines of code. Make sure to use the namespaces System.IO and System.Linq.

private static long GetDirectorySize(string folderPath)
{
    DirectoryInfo di = new DirectoryInfo(folderPath);
    return di.EnumerateFiles("*.*", SearchOption.AllDirectories).Sum(fi => fi.Length);
}

Answer 2

If you use Directory.GetFiles you can do a recursive seach (using SearchOption.AllDirectories), but this is a bit flaky anyway (especially if you don't have access to one of the sub-directories) - and might involve a huge single array coming back (warning klaxon...).

I'd be happy with the recursion approach unless I could show (via profiling) a bottleneck; and then I'd probably switch to (single-level) Directory.GetFiles, using a Queue<string> to emulate recursion.

Note that .NET 4.0 introduces some enumerator-based file/directory listing methods which save on the big arrays.