ACC: Enumerating Local and Network Printers (166008)

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WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN RISK. Microsoft provides this code "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.

Use the Sub routine EnumeratePrinters1 if you are running Microsoft Windows 95 or later. You can use either Sub routine if you are running Microsoft Windows NT.

The code in each of the two examples performs these steps:

• Calls the EnumPrinters API, which returns a buffer of data, a success flag, and a flag indicating whether the buffer is too small.
• If the buffer is too small, makes it the correct size and calls the API again.
• For each entry in the buffer, extracts the data and prints it.

NOTE: When using these functions in your own applications, you may want to return an array of data that can be displayed in a list box or grid rather than print the values.

The buffer is in the following format: INFO records containing string pointers and numeric values are added from the left, and the string text for each record is added from the right. The area between the end of the last record and the start of the last string text contains garbage.

The buffer is declared as type Long, which makes extracting data from the records easier - all fields are either Long or pointers (pointers map to Long).

The StrLen() and PtrToStr() functions are used to set up the receiving string variable and to copy the text from the buffer to the variable.

1. Create a module and type the following lines in the Declarations section:

         Option Explicit
   
         Const PRINTER_ENUM_CONNECTIONS = &H4
         Const PRINTER_ENUM_LOCAL = &H2
   
         Type PRINTER_INFO_1
            flags As Long
            pDescription As String
            PName As String
            PComment As String
         End Type
   
         Type PRINTER_INFO_4
            pPrinterName As String
            pServerName As String
            Attributes As Long
         End Type
   
         Declare Function EnumPrinters Lib "winspool.drv" Alias _
            "EnumPrintersA" (ByVal flags As Long, ByVal name As String, _
            ByVal Level As Long, pPrinterEnum As Long, ByVal cdBuf As Long, _
            pcbNeeded As Long, pcReturned As Long) As Long
         Declare Function PtrToStr Lib "Kernel32" Alias "lstrcpyA" _
            (ByVal RetVal As String, ByVal Ptr As Long) As Long
         Declare Function StrLen Lib "Kernel32" Alias "lstrlenA" _
            (ByVal Ptr As Long) As Long
   					

2. Type the following procedures:

         Sub EnumeratePrinters1()
         Dim Success As Boolean, cbRequired As Long, cbBuffer As Long
         Dim Buffer() As Long, nEntries As Long
         Dim I As Long, PFlags As Long, PDesc As String, PName As String
         Dim PComment As String, Temp As Long
            cbBuffer = 3072
            ReDim Buffer((cbBuffer \ 4) - 1) As Long
            Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
                                  PRINTER_ENUM_LOCAL, _
                                  vbNullString, _
                                  1, _
                                  Buffer(0), _
                                  cbBuffer, _
                                  cbRequired, _
                                  nEntries)
            If Success Then
               If cbRequired > cbBuffer Then
                  cbBuffer = cbRequired
                  Debug.Print "Buffer too small.  Trying again with " & _
                           cbBuffer & " bytes."
                  ReDim Buffer(cbBuffer \ 4) As Long
                  Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
                                      PRINTER_ENUM_LOCAL, _
                                      vbNullString, _
                                      1, _
                                      Buffer(0), _
                                      cbBuffer, _
                                      cbRequired, _
                                      nEntries)
                  If Not Success Then
                     Debug.Print "Error enumerating printers."
                     Exit Sub
                  End If
               End If
            Debug.Print "There are " & nEntries & _
                         " local and connected printers."
            For I = 0 To nEntries - 1
               PFlags = Buffer(4 * I)
               PDesc = Space$(StrLen(Buffer(I * 4 + 1)))
               Temp = PtrToStr(PDesc, Buffer(I * 4 + 1))
               PName = Space$(StrLen(Buffer(I * 4 + 2)))
               Temp = PtrToStr(PName, Buffer(I * 4 + 2))
               PComment = Space$(StrLen(Buffer(I * 4 + 2)))
               Temp = PtrToStr(PComment, Buffer(I * 4 + 2))
               Debug.Print PFlags, PDesc, PName, PComment
            Next I
            Else
               Debug.Print "Error enumerating printers."
            End If
         End Sub
   
         Sub EnumeratePrinters4()
         Dim Success As Boolean, cbRequired As Long, cbBuffer As Long
         Dim Buffer() As Long, nEntries As Long
         Dim I As Long, PName As String, SName As String
         Dim Attrib As Long, Temp As Long
            cbBuffer = 3072
            ReDim Buffer((cbBuffer \ 4) - 1) As Long
            Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
                                  PRINTER_ENUM_LOCAL, _
                                  vbNullString, _
                                  4, _
                                  Buffer(0), _
                                  cbBuffer, _
                                  cbRequired, _
                                  nEntries)
            If Success Then
               If cbRequired > cbBuffer Then
                  cbBuffer = cbRequired
                  Debug.Print "Buffer too small.  Trying again with " & _
                           cbBuffer & " bytes."
                  ReDim Buffer(cbBuffer \ 4) As Long
                  Success = EnumPrinters(PRINTER_ENUM_CONNECTIONS Or _
                                      PRINTER_ENUM_LOCAL, _
                                      vbNullString, _
                                      4, _
                                      Buffer(0), _
                                      cbBuffer, _
                                      cbRequired, _
                                      nEntries)
                  If Not Success Then
                     Debug.Print "Error enumerating printers."
                     Exit Sub
                  End If
               End If
               Debug.Print "There are " & nEntries & _
                         " local and connected printers."
               For I = 0 To nEntries - 1
               PName = Space$(StrLen(Buffer(I * 3)))
               Temp = PtrToStr(PName, Buffer(I * 3))
               SName = Space$(StrLen(Buffer(I * 3 + 1)))
               Temp = PtrToStr(SName, Buffer(I * 3 + 1))
               Attrib = Buffer(I * 3 + 2)
               Debug.Print "Printer: " & PName, "Server: " & SName, _
                           "Attributes: " & Hex$(Attrib)
               Next I
            Else
               Debug.Print "Error enumerating printers."
            End If
         End Sub
   					

3. To test this function, type the following line in the Debug window, and then press ENTER:

   EnumeratePrinters1

   The output should be similar to the following:

          There are 1 local and connected printers.
          8388608      \\NCPRINT\HP5SI@1155,HP LaserJet 5Si MX,HP5SI@1155
          \\NCPRINT\HP5SI@1155        \\NCPRINT\HP5SI@1155
   						

   If you are using Microsoft Windows NT, type:

   EnumeratePrinters4

   The output should be similar to the following:

          There are 1 local and connected printers.
          Printer: \\NCPRINT\HP5SI@1155             Server: \\NCPRINT
          Attributes: 10