KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q291575: HOWTO: Use Visual Basic to Locate CD-ROM Drives

Article: Q291575
Product(s): Microsoft Visual Basic for Windows
Version(s): 5.0,6.0
Operating System(s): 
Keyword(s): kbsample kbAPI kbSDKWin32 kbVBp kbVBp500 kbVBp600 kbGrpDSVB kbDSupport
Last Modified: 31-MAR-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
-------------------------------------------------------------------------------

SUMMARY
=======

You can find the drive letter of any CD-ROM drive on a local computer by using
the Win32 API from Visual Basic. This can be useful during scenarios such as
program setup and querying a user for media.

MORE INFORMATION
================

You can use the GetDriveType API to determine the type of drive referenced by a
drive letter. By combining this API with a list of the active drive letters on a
computer, you can search for CD-ROM drives available on that computer. Note that
the API does not distinguish between types of CD-ROM drives, so for example, a
DVD drive is considered a CD-ROM drive.

The following code sample demonstrates how to search for local CD-ROM drives by
using Visual Basic.

Sample Code
-----------

1. Start a new Visual Basic Standard EXE project. Form1 is created by default.

2. Add a new command button (Command1) to Form1.

3. Add the following code to Form1's code window:

  Option Explicit

  Private Declare Function GetDriveType Lib "kernel32" Alias "GetDriveTypeA" _
      (ByVal nDrive As String) As Long

  Private Declare Function GetLogicalDriveStrings Lib "kernel32" _
      Alias "GetLogicalDriveStringsA" _
      (ByVal nBufferLength As Long, ByVal lpBuffer As String) As Long

  Const DRIVE_CDROM& = 5

  Public Function GetDriveStrings() As String
      ' Wrapper for calling the GetLogicalDriveStrings api
      
      Dim result As Long          ' Result of our API calls
      Dim strDrives As String     ' String to pass to API call
      Dim lenStrDrives As Long    ' Length of the above string
      
      ' Call GetLogicalDriveStrings with a buffer size of zero to
      ' find out how large our stringbuffer needs to be
      result = GetLogicalDriveStrings(0, strDrives)
      
      strDrives = String(result, 0)
      lenStrDrives = result
      
      ' Call again with our new buffer
      result = GetLogicalDriveStrings(lenStrDrives, strDrives)
      
      If result = 0 Then
          ' There was some error calling the API
          ' Pass back an empty string
          ' NOTE - TODO: Implement proper error handling here
          GetDriveStrings = ""
      Else
          GetDriveStrings = strDrives
      End If
  End Function

  Private Sub Command1_Click()
      Dim strDrives As String
      
      ' Find out what drives we have on this machine
      strDrives = GetDriveStrings()
      
      If strDrives = "" Then
          ' No drives were found
          MsgBox "No Drives were found!", vbCritical
      Else
          ' Walk through the string and check the type of each drive
          ' displaying any cd-rom drives we find
          Dim pos As Long
          Dim drive As String
          Dim drivetype As Long
          
          pos = 1
          
          Do While Not Mid$(strDrives, pos, 1) = Chr(0)
              drive = Mid$(strDrives, pos, 3)
              pos = pos + 4
              drivetype = GetDriveType(drive)
              If drivetype = DRIVE_CDROM Then
                  MsgBox "CD-ROM found at drive " & UCase(drive)
              End If
          Loop
      End If
  End Sub
   

4. Click Run or press the F5 key to run the project.

Result: Any CD-ROM drives on the computer are displayed by drive letter in a
message box.

REFERENCES
==========

For additional information, click the article numbers below to view the articles
in the Microsoft Knowledge Base:

  Q190000 HOWTO: Get Started Programming with the Windows API

  Q180766 VBA: Sample Code to Determine CD-ROM Drive Letter

  Q291573 HOWTO: Use Visual Basic to List Active Logical Drives

The Visual Basic Programmer's Guide (available on MSDN Online,
http://msdn.microsoft.com/default.asp)

(c) Microsoft Corporation 2001, All Rights Reserved.
Contributions by Gray McDonald, Microsoft Corporation


Additional query words: VB CD CDROM Locate Drive Find List

======================================================================
Keywords          : kbsample kbAPI kbSDKWin32 kbVBp kbVBp500 kbVBp600 kbGrpDSVB kbDSupport 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Version           : :5.0,6.0
Issue type        : kbhowto

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.