Q141020: How to Find Next Available Drive Letter (for Network Connect)

Article: Q141020
Product(s): Microsoft Visual Basic for Windows
Version(s): 4.00
Operating System(s): 
Keyword(s): kbcode kbnetwork
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 
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SUMMARY
=======

The Visual Basic program in this article shows by example how to find the next
available (unused) drive letter in Windows. This is useful when making network
connections to a new drive letter.

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

Step-by-Step Example
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The Freedrive function defined below returns the next drive letter available in
Windows, followed by a colon (:).

1. Start Visual Basic. Form1 is created by default.

2. Add the following code to the General Declarations section of Form1:

  #If Win32 Then
    Private Declare Function GetDriveType Lib "kernel32" Alias
  "GetDriveTypeA" (ByVal nDrive As String) As Long
  #Else
    Private Declare Function GetDriveType Lib "kernel" (ByVal nDrive As
  Integer) As Integer
  #End If

  Function Freedrive()
        Dim DriveNum As Integer, FirstFreeDrive As String
        Dim FirstDrive As Integer
        DriveNum = -1
        Do
           DriveNum = DriveNum + 1   ' start at drive zero.
           #If Win32 Then
             NextDrive$ = Chr$(DriveNum + 65) + ":\"
             FirstDrive% = GetDriveType(NextDrive$)
           #Else
             FirstDrive% = GetDriveType(DriveNum)
           #End If
           ' GetDriveType returns zero if it cannot determine drive
           ' type or returns 1 if the specified drive does not exist.
        #If Win32 Then
          Loop Until FirstDrive% = 1
        #Else
          Loop Until FirstDrive% = 0
        #End If
        ' DriveNum of 0 means Drive A, 1=B, 2=C, 3=D, 4=E, 5=F, and so on:
        FirstFreeDrive = Chr$(DriveNum + 65) + ":"
        Freedrive = FirstFreeDrive
  End Function

3. In the Form_click event, add the following statements:

     Private Sub Form_Click ()

        Cls
        Print "The next available (unused) drive letter is: "; Freedrive()

        ' More handy tips: The "App" object below is found in VB 2.0
        ' and 3.0 (but not 1.0).
        Print "The title for the EXE in Windows Task Manager: "; app.Title
        Print "The name of this EXE, or project in VB, is: "; app.EXEName
        Print "The path to this application is: "; app.Path

     End Sub

4. Run the program, and click the form.

Additional query words: 2.00 3.00 4.00 vb4win vb4all

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Keywords          : kbcode kbnetwork 
Technology        : kbVBSearch kbAudDeveloper kbVB400Search kbVB400 kbVB16bitSearch
Version           : 4.00

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