How To Get UNC Path From a Mapped Network Share's Drive Letter

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Most network client software allows you to refer to network drives through the use of mapped drive letters or the use of syntax known as UNC notation (Universal Naming Convention). Use of UNC notation requires that you know the name of the server and share, while a mapped drive letter only requires the drive letter once the connection has been established. At times, it may be necessary to determine the UNC path to a server given only it's mapped drive letter. This article demonstrates a method for obtaining this information.

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Step-by-Step Example

  1. Map a drive letter to any available network share and make note of the letter assigned.
  2. Create a new Visual Basic project. Form1 is created by default.
  3. Add a CommandButton to Form1.
  4. Paste the following code into Form1's code window:
          Option Explicit
          Private Const RESOURCETYPE_ANY = &H0
          Private Const RESOURCE_CONNECTED = &H1
          Private Type NETRESOURCE
             dwScope As Long
             dwType As Long
             dwDisplayType As Long
             dwUsage As Long
             lpLocalName As Long
             lpRemoteName As Long
             lpComment As Long
             lpProvider As Long
          End Type
          Private Declare Function WNetOpenEnum Lib "mpr.dll" Alias _
             "WNetOpenEnumA" (ByVal dwScope As Long, ByVal dwType As Long, _
             ByVal dwUsage As Long, lpNetResource As Any, lphEnum As Long) _
             As Long
          Private Declare Function WNetEnumResource Lib "mpr.dll" Alias _
             "WNetEnumResourceA" (ByVal hEnum As Long, lpcCount As Long, _
             lpBuffer As Any, lpBufferSize As Long) As Long
          Private Declare Function WNetCloseEnum Lib "mpr.dll" ( _
             ByVal hEnum As Long) As Long
          Private Declare Function lstrlen Lib "kernel32" Alias "lstrlenA" _
             (ByVal lpString As Any) As Long
          Private Declare Function lstrcpy Lib "kernel32" Alias "lstrcpyA" _
             (ByVal lpString1 As Any, ByVal lpString2 As Any) As Long
          Private Sub Command1_Click()
             MsgBox LetterToUNC("F:") ' <<<<<<<<<<<<<<<<<<<<<<<<<<<<<
          End Sub
          Function LetterToUNC(DriveLetter As String) As String
             Dim hEnum As Long
             Dim NetInfo(1023) As NETRESOURCE
             Dim entries As Long
             Dim nStatus As Long
             Dim LocalName As String
             Dim UNCName As String
             Dim i As Long
             Dim r As Long
             ' Begin the enumeration
             nStatus = WNetOpenEnum(RESOURCE_CONNECTED, RESOURCETYPE_ANY, _
                0&, ByVal 0&, hEnum)
             LetterToUNC = "Drive Letter Not Found"
             'Check for success from open enum
             If ((nStatus = 0) And (hEnum <> 0)) Then
                ' Set number of entries
                entries = 1024
                ' Enumerate the resource
                nStatus = WNetEnumResource(hEnum, entries, NetInfo(0), _
                   CLng(Len(NetInfo(0))) * 1024)
                ' Check for success
                If nStatus = 0 Then
                   For i = 0 To entries - 1
                      ' Get the local name
                      LocalName = ""
                      If NetInfo(i).lpLocalName <> 0 Then
                         LocalName = Space(lstrlen(NetInfo(i).lpLocalName) + 1)
                         r = lstrcpy(LocalName, NetInfo(i).lpLocalName)
                      End If
                      ' Strip null character from end
                      If Len(LocalName) <> 0 Then
                         LocalName = Left(LocalName, (Len(LocalName) - 1))
                      End If
                      If UCase$(LocalName) = UCase$(DriveLetter) Then
                         ' Get the remote name
                         UNCName = ""
                         If NetInfo(i).lpRemoteName <> 0 Then
                            UNCName = Space(lstrlen(NetInfo(i).lpRemoteName) _
                               + 1)
                            r = lstrcpy(UNCName, NetInfo(i).lpRemoteName)
                         End If
                         ' Strip null character from end
                         If Len(UNCName) <> 0 Then
                            UNCName = Left(UNCName, (Len(UNCName) _
                               - 1))
                         End If
                         ' Return the UNC path to drive
                         LetterToUNC = UNCName
                         ' Exit the loop
                         Exit For
                      End If
                   Next i
                End If
             End If
             ' End enumeration
             nStatus = WNetCloseEnum(hEnum)
          End Function
  5. Change the code in Command1's Click event to refer to the drive letter created by step 1.
  6. Run the sample.
  7. Click the CommandButton. The UNC path to the mapped drive is shown in a message box.


Article ID: 192689 - Last Review: June 22, 2014 - Revision: 5.0
Applies to
  • Microsoft Visual Basic 5.0 Learning Edition
  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition
  • Microsoft Visual Basic 5.0 Control Creation Edition
  • Microsoft Visual Basic 4.0 Standard Edition
kbhowto KB192689

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