c#如何返回系统中所有可用驱动器符号？

// The initial C# code for the "plain" WMI query was generated by
// WMI Code Generator, Version 5.00, //http://www.robvanderwoude.com/wmigen.php
using System;
using System.Management;
using System.Collections.Generic;
namespace RobvanderWoude
{
 public class ListDrives
 {
  public static int Main( string[] args )
  {
   try
   {
    string computer = string.Empty;
    #region Command line parsing
    // Only 1 optional argument allowed: a remote computer name
    if ( args.Length > 1 )
    {
throw new Exception( "Invalid command line arguments" );
    }
    if ( args.Length == 1 )
    {
// We'll display a 'friendly' message if help was requested
if ( args[0].StartsWith( "/" ) || args[0].StartsWith( "-" ) )
{
 switch ( args[0].ToUpper( ) )
 {
  case "/?":
  case "-?":
  case "/H":
  case "-H":
  case "--H":
  case "/HELP":
  case "-HELP":
  case "--HELP":
   return WriteError( string.Empty );
  default:
   return WriteError( "Invalid command line argument" );
 }
}
else
{
 computer = "\" + args[0] + "";
}
    }
    #endregion
    string wmins = computer + "rootCIMV2";
    ManagementObjectSearcher searcher = new ManagementObjectSearcher( wmins, "SELECT * FROM Win32_LogicalDisk" );
    List<string> drives = new List<string>( );
    foreach ( ManagementObject queryObj in searcher.Get( ) )
    {
drives.Add( queryObj["DeviceID"].ToString( ) );
    }
    drives.Sort( );
    string drivelist = "";
    foreach ( string drive in drives )
    {
drivelist += ( drive + " " );
    }
    Console.WriteLine( drivelist.Trim( ) );
    return 0;
   }
   catch ( Exception e )
   {
    return WriteError( e );
   }
  }
  public static int WriteError( Exception e )
  {
   return WriteError( e == null ? null : e.Message );
  }
  public static int WriteError( string errorMessage )
  {
   string fullpath = Environment.GetCommandLineArgs( ).GetValue( 0 ).ToString( );
   string[] program = fullpath.Split( '' );
   string exename = program[program.GetUpperBound( 0 )];
   exename = exename.Substring( 0, exename.IndexOf( '.' ) );
   if ( string.IsNullOrEmpty( errorMessage ) == false )
   {
    Console.Error.WriteLine( );
    Console.ForegroundColor = ConsoleColor.Red;
    Console.Error.Write( "ERROR: " );
    Console.ForegroundColor = ConsoleColor.White;
    Console.Error.WriteLine( errorMessage );
    Console.ResetColor( );
   }
   Console.Error.WriteLine( );
   Console.Error.WriteLine( exename + ", Version 1.10" );
   Console.Error.WriteLine( "List all drive letters in use on the specified computer" );
   Console.Error.WriteLine( );
   Console.Error.Write( "Usage: " );
   Console.ForegroundColor = ConsoleColor.White;
   Console.Error.Write( exename.ToUpper( ) );
   Console.Error.WriteLine( " [ computername ]" );
   Console.ResetColor( );
   Console.Error.WriteLine( );
   Console.Error.WriteLine( "Where: 'computername' is the (optional) name of a remote computer" );
   Console.Error.WriteLine( " (default if not specified: local computer)" );
   Console.Error.WriteLine( );
   Console.Error.WriteLine( "Written by Rob van der Woude" );
   return 1;
  }
 }
}