using System;

public class Program

{

    public static void Main()

    {

    System.IO.DirectoryInfo cDirs = new System.IO.DirectoryInfo(@"/");

            // Write each directory name to a file.

        System.IO.FileInfo f= new System.IO.FileInfo("CDriveDirs.txt");

using (System.IO.StreamWriter sw = new System.IO.StreamWriter(f.open))

{

    foreach (System.IO.DirectoryInfo dir in (cDirs.GetDirectories()))

    {

        sw.WriteLine(dir.Name);

    }

}

// Read and show each line from the file.

string line = "";

using (System.IO.StreamReader sr = new System.IO.StreamReader("CDriveDirs.txt"))

{

    while ((line = sr.ReadLine()) != null)

    {

        Console.WriteLine(line);

    }

}

    }

}

​