Detecting if a printer is installed

Hi darkrain,

This example uses some api calls to enumerate locally installed printers. You could modify this to simply return a count of the printers installed and use the existing If statement that checks for more than one to show your message box error.

' Get information about all of the local printers using structure 1.  Note how
' the elements of the array are loaded into an array of data structures manually.  Also
' note how the following special declares must be used to allow numeric string pointers
' to be used in place of strings:
Private Declare Function lstrcpy Lib "kernel32.dll" Alias "lstrcpyA" (ByVal lpString1 As String, ByVal lpString2 As Long) As Long
Private Declare Function lstrlen Lib "kernel32.dll" Alias "lstrlenA" (ByVal lpString As Long) As Long
Private 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
Const PRINTER_ENUM_LOCAL = &H2
Private Type PRINTER_INFO_1
        flags As Long
        pDescription As String
        pName As String
        pComment As String
End Type
Private Sub Form_Load()
    'KPD-Team 1999
    'URL: http://www.allapi.net/
    'E-Mail: KPDTeam@Allapi.net
    Dim longbuffer() As Long  ' resizable array receives information from the function
    Dim printinfo() As PRINTER_INFO_1  ' values inside longbuffer() will be put into here
    Dim numbytes As Long  ' size in bytes of longbuffer()
    Dim numneeded As Long  ' receives number of bytes necessary if longbuffer() is too small
    Dim numprinters As Long  ' receives number of printers found
    Dim c As Integer, retval As Long  ' counter variable & return value
    Me.AutoRedraw = True 'Set current graphic mode to persistent
    ' Get information about the local printers
    numbytes = 3076  ' should be sufficiently big, but it may not be
    ReDim longbuffer(0 To numbytes / 4) As Long  ' resize array -- note how 1 Long = 4 bytes
    retval = EnumPrinters(PRINTER_ENUM_LOCAL, "", 1, longbuffer(0), numbytes, numneeded, numprinters)
    If retval = 0 Then  ' try enlarging longbuffer() to receive all necessary information
        numbytes = numneeded
        ReDim longbuffer(0 To numbytes / 4) As Long  ' make it large enough
        retval = EnumPrinters(PRINTER_ENUM_LOCAL, "", 1, longbuffer(0), numbytes, numneeded, numprinters)
        If retval = 0 Then ' failed again!
            Debug.Print "Could not successfully enumerate the printes."
        End  ' abort program
    End If
    End If
    ' Convert longbuffer() data into printinfo()
    If numprinters <> 0 Then ReDim printinfo(0 To numprinters - 1) As PRINTER_INFO_1 ' room for each printer
    For c = 0 To numprinters - 1  ' loop, putting each set of information into each element
        ' longbuffer(4 * c) = .flags, longbuffer(4 * c + 1) = .pDescription, etc.
        ' For each string, the string is first buffered to provide enough room, and then the string is copied.
        printinfo(c).flags = longbuffer(4 * c)
        printinfo(c).pDescription = Space(lstrlen(longbuffer(4 * c + 1)))
        retval = lstrcpy(printinfo(c).pDescription, longbuffer(4 * c + 1))
        printinfo(c).pName = Space(lstrlen(longbuffer(4 * c + 2)))
        retval = lstrcpy(printinfo(c).pName, longbuffer(4 * c + 2))
        printinfo(c).pComment = Space(lstrlen(longbuffer(4 * c + 3)))
        retval = lstrcpy(printinfo(c).pComment, longbuffer(4 * c + 3))
    Next c
    ' Display name of each printer
    For c = 0 To numprinters - 1
        Me.Print "Name of printer"; c + 1; " is: "; printinfo(c).pName
    Next c
End Sub


Tim Cottee MCSD, MCDBA, CPIM
Brainbench MVP for Visual Basic
http://www.brainbench.com