Microsoft KB Archive/200611

= ACC2000: Enumerating Local and Network Printers =

Article ID: 200611

Article Last Modified on 10/11/2006

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APPLIES TO


 * Microsoft Access 2000 Standard Edition

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This article was previously published under Q200611



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



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

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.



MORE INFORMATION
Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. 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, the code makes it the correct size and calls the API again.
 * For each entry in the buffer, it 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 Compare Database 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 EnumeratePrintersWin

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 EnumeratePrintersNT

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 Immediate window, and then press ENTER: EnumeratePrintersWIN 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: EnumeratePrintersNT The output should be similar to the following:

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



