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Microsoft KB Archive/100834

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Knowledge Base

Article ID: 100834

Article Last Modified on 12/9/2003


  • Microsoft Visual Basic 2.0 Standard Edition
  • Microsoft Visual Basic 3.0 Professional Edition
  • Microsoft Visual Basic 2.0 Professional Edition
  • Microsoft Visual Basic 3.0 Professional Edition

This article was previously published under Q100834


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


Step-by-Step Example

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:

       ' Enter the following Declare statement as one, single line:
       Declare Function GetDriveType Lib "kernel"
          (ByVal nDrive As Integer) As Integer
       Function Freedrive ()
          Dim DriveNum As Integer, FirstFreeDrive As String
          Dim FirstDrive As Integer
          DriveNum = -1
             DriveNum = DriveNum + 1   ' start at drive zero.
             FirstDrive% = GetDriveType(DriveNum)
             ' GetDriveType returns zero if it cannot determine drive
             ' type or returns 1 if the specified drive does not exist.
          Loop Until FirstDrive% = 0
          ' 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:

       Sub Form_Click ()
          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

Keywords: kbnetwork kbcode KB100834