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

Solution 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);
}

Solution 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.

Solution 3:

Here my .NET 4.0 approach

public static long GetFileSizeSumFromDirectory(string searchDirectory)
{
 var files = Directory.EnumerateFiles(searchDirectory);

 // get the sizeof all files in the current directory
 var currentSize = (from file in files let fileInfo = new FileInfo(file) select fileInfo.Length).Sum();

 var directories = Directory.EnumerateDirectories(searchDirectory);

 // get the size of all files in all subdirectories
 var subDirSize = (from directory in directories select GetFileSizeSumFromDirectory(directory)).Sum();

 return currentSize + subDirSize;
}

Or even nicer:

// get IEnumerable from all files in the current dir and all sub dirs
var files = Directory.EnumerateFiles(searchDirectory,"*",SearchOption.AllDirectories);

// get the size of all files
long sum = (from file in files let fileInfo = new FileInfo(file) select fileInfo .Length).Sum();

As Gabriel pointed out this will fail if you have a restricted directory under the searchDirectory!