[C#][Extension Method]Get directory size

namespace ConsoleApplication8 { class Program { static void Main(string[] args) { GetFolderSize(@“C:\Program Files”); GetDirSize(@“C:\Program Files”); DirSize(new DirectoryInfo(@“C:\Program Files”));

		var sw = Stopwatch.StartNew();
		Console.WriteLine(GetFolderSize(@"C:\Program Files"));
		Console.WriteLine(sw.ElapsedMilliseconds);

		sw.Stop();
		sw.Reset();
		sw.Start();

		Console.WriteLine(GetDirSize(@"C:\Program Files"));
		Console.WriteLine(sw.ElapsedMilliseconds);

		sw.Stop();
		sw.Reset();
		sw.Start();

		Console.WriteLine(DirSize(new DirectoryInfo(@"C:\Program Files")));
		Console.WriteLine(sw.ElapsedMilliseconds);
	}

	static long GetDirSize(string path)
	{
		return (from item in Directory.GetFiles(path, "*.*", SearchOption.AllDirectories)
				select new FileInfo(item).Length).Sum();
	}

	static long GetFolderSize(string folder) // 取得資料夾大小 
	{
		return long.Parse((new Scripting.FileSystemObjectClass()).GetFolder(folder).Size.ToString());
	}

	public static long DirSize(DirectoryInfo d)
	{
		long Size = 0;
		// Add file sizes.
		FileInfo[] fis = d.GetFiles();
		foreach (FileInfo fi in fis)
		{
			Size += fi.Length;
		}
		// Add subdirectory sizes.
		DirectoryInfo[] dis = d.GetDirectories();
		foreach (DirectoryInfo di in dis)
		{
			Size += DirSize(di);
		}
		return (Size);
	}
}

}

public static class DirectoryInfoExtension { public static long GetSize(this DirectoryInfo dirInfo) { Type tp = Type.GetTypeFromProgID(“Scripting.FileSystemObject”); object fso = Activator.CreateInstance(tp); object fd = tp.InvokeMember(“GetFolder”, BindingFlags.InvokeMethod, null, fso, new object[] { dirInfo.FullName }); long ret = Convert.ToInt64(tp.InvokeMember(“Size”, BindingFlags.GetProperty, null, fd, null)); Marshal.ReleaseComObject(fso); return ret; } }

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