How do I get a human-readable file size in bytes abbreviation using .NET?

From stackoverflow:

string[] sizes = { "B", "KB", "MB", "GB" };
double len = new FileInfo(filename).Length;
int order = 0;
while (len >= 1024 && order + 1 < sizes.Length) {
    order++;
    len = len/1024;
}

// Adjust the format string to your preferences. For example "{0:0.#}{1}" would
// show a single decimal place, and no space.
string result = String.Format("{0:0.##} {1}", len, sizes[order]);