Microsoft KB Archive/166008

= ACC: Enumerating Local and Network Printers =

Article ID: 166008

Article Last Modified on 1/19/2007

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APPLIES TO


 * Microsoft Access 95 Standard Edition
 * Microsoft Access 97 Standard Edition

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This article was previously published under Q166008



SUMMARY
Advanced: Requires expert coding, interoperability, and multiuser skills.

This article shows you two procedures that use the EnumPrinters API function to retrieve a list of printers available locally and that your computer is connected to on the network.

The procedures demonstrate returning data to both the PRINTER_INFO_1 structure and the PRINTER_INFO_4 structure, each of which provides slightly different information about the printer. If you are using Microsoft Windows 95 or later, you can return data to the PRINTER_INFO_1 structure; if you are using Microsoft Windows NT, you can return data to either structure.

This article assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to your version of the "Building Applications with Microsoft Access" manual.



MORE INFORMATION
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:


 * rec1|rec2|...|recn|...garbage...|strn|...|str2|str1|

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.

  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   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   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 

