All Directories traverses all sub-directories under the root : Directory « File Directory Stream « C# / CSharp Tutorial

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.IO.Compression;
using System.Net;
using System.Net.Mail;
using System.Net.Sockets;
using System.Runtime.InteropServices;
using System.Text;

public class MainClass
{
    public static void Main()
    {
        DirectoryInfo root = new DirectoryInfo(@"C:\Program Files\");

        DirectoryInfo[] dirs = root.GetDirectories("*", SearchOption.TopDirectoryOnly);
        Console.WriteLine("{0} subdirectories:", root.FullName);
        foreach (DirectoryInfo subDir in dirs)
        {
            Console.WriteLine("    {0}", subDir.Name);
        }

    }
}

C:\Program Files\ subdirectories:
    Adobe
    AMD
    ATI Technologies
    Common Files
    ComPlus Applications
    CONEXANT

15.15.Directory
	15.15.1.	Get the files from the root directory
	15.15.2.	Use file filer on a directory
	15.15.3.	Directory.Exists
	15.15.4.	Get Current Directory
	15.15.5.	Get relative path
	15.15.6.	Changing current directory to c:\\
	15.15.7.	Delete Directory
	15.15.8.	Directory Attributes
	15.15.9.	Use DirectoryInfo to create sub directory
	15.15.10.	List directory under a directory
	15.15.11.	List files under a directory
	15.15.12.	All Directories traverses all sub-directories under the root
	15.15.13.	Traverse all files under the root
	15.15.14.	Recursive Directory use
	15.15.15.	Get DirectoryInfo from FileInfo: name, parent directory name, directory exists
	15.15.16.	DirectoryInfo: creation time, last write time, last access time
	15.15.17.	DirectoryInfo: Directory attribute list and Directory contains
	15.15.18.	Using Directory type
	15.15.19.	Recursely Explore Directories
	15.15.20.	Show basic directory info
	15.15.21.	Modify directory structure
	15.15.22.	Creating Subdirectory and Manipulating File
	15.15.23.	Exploring Files And Sub directories
	15.15.24.	Create directory structure
	15.15.25.	Get all cs file from current directory, display its creation time, length, name
	15.15.26.	Use the GetFiles method to return file names from a user-specified location.