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

Most network client software allows you to refer to network drives throughthe use of mapped drive letters or the use of syntax known as UNC notation(Universal Naming Convention). Use of UNC notation requires that you knowthe name of the server and share, while a mapped drive letter only requiresthe drive letter once the connection has been established. At times, it maybe necessary to determine the UNC path to a server given only it's mappeddrive letter. This article demonstrates a method for obtaining thisinformation.
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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.
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Article ID: 192689 - Last Review: 06/22/2014 19:16:00 - Revision: 5.0

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