Visual Basic and PureBasic DLLs

[neomancer]

How do i make a DLL for a Visual Basic program?

i need to return a string, but VB keeps crashing. 8O

any help?

[fweil]

neomancer,

Do you need a bytes string or a BSTR ?

Returning the string passes the address to this string.

If you need a BSTR instead of regular ASCII string, you will have to use a conversion procedure, easy to find here.

Rgrds

[neomancer]

well basically i want to see if i can pass a text file out of the dll

so it would be ASCII, i dont know much about Purebasic.

Its a project i wrote years back, you pass a whole readme.txt and it jumbles up the text file and passes it back

<vb code>

newstring$ = MyFunction(textfromfile$)

(myfunction is from the PureBasic Dll declaration)

if it is the address of the string by this you mean pointer?

[fweil]

the Procedure or ProcedureDLL would look like that :

Code: Select all

Procedure.s MyFunction(FileName.s)
  Result.s = ""
  If ReadFile(99, FileName)
      LengthOfFile.l = Lof()
      *Buffer = AllocateMemory(LengthOfFile)
      ReadData(*Buffer, LengthOfFile)
      CloseFile(99)
      Result.s = PeekS(*Buffer)
      FreeMemory(*Buffer)
  EndIf
  ProcedureReturn Result
EndProcedure

;
; test code
;
  Debug MyFunction("C:\test.txt")

[neomancer]

wow i realy dont know whats going on here

ok.

how do i get a procedureDLL to return the string "Your string is returned"

this is for a VB project

[Edwin Knoppert]

1) Create mem using: SysAllocStringByteLen() API.
2) The resulting pointer should be returned in your proceduredll.L << Note the L
3) MAKE SURE VB is declared as string, this will release the created memory by VB as should.

So pb returns a long, the address of the memory.

Yes, the 100% desire BSTR that is!
(Which pb should implement imo)

[Edwin Knoppert]

Forgot to mention, you should pass desired .s data to this sysalloc.. api.
or use movememory(), whatever..

[neomancer]

have you got an example?
for both pb and vb
i dont know how this stuff work at all! i come from a background of BlitzBasic (they dumbed me!)

[Edwin Knoppert]

A bit bloathed, used PBDev

Purebasic part:

Code: Select all

;=========================================================
; PBDev PureBasic Developer, 1.00, 2004-06-04, 15:04
;=========================================================

#PBD_DLL = 1




Global PBD_App_hInstance.l
Global PBD_App_Title.s
Global PBD_LasthWnd.l



ProcedureDLL.l TEST()

    Protected pBSTR.l
    Protected s.s
    Protected nLen.l
        
    s = "1234567890"

    pBSTR = SysAllocStringByteLen_( s, Len( s ) )
    nLen = SysStringByteLen_( pBSTR )

    MessageRequester( "Purebasic", PeekS( pBSTR, nLen ), 0 )

    ProcedureReturn pBSTR

EndProcedure


Procedure.l PBD_Initialize()
    PBD_LasthWnd = 0
    PBD_App_hInstance = GetModuleHandle_(0)
    PBD_App_Title = ""
EndProcedure


Procedure.l PBD_LibMain( hInstance, nReason )

    Select nReason
    Case 1  ; DLL_PROCESS_ATTACH
    Case 0  ; DLL_PROCESS_DETACH
    Case 2  ; DLL_THREAD_ATTACH
    Case 3  ; DLL_THREAD_DETACH
    EndSelect

    ProcedureReturn 1

EndProcedure

ProcedureDLL AttachProcess( hInstance )
    PBD_App_hInstance = hInstance
    ProcedureReturn PBD_LibMain( hInstance, 1 )
EndProcedure

ProcedureDLL DetachProcess( hInstance )
    ProcedureReturn PBD_LibMain( hInstance, 0 )
EndProcedure

ProcedureDLL AttachThread( hInstance )
    ProcedureReturn PBD_LibMain( hInstance, 2 )
EndProcedure

ProcedureDLL DetachThread( hInstance )
    ProcedureReturn PBD_LibMain( hInstance, 3 )
EndProcedure

VB part:

Code: Select all

Option Explicit

Private Declare Function TEST Lib "D:\TEMP\PB70E6\unsaved.dll" () As String

Private Sub Form_Load()

    MsgBox TEST()

End Sub

[fweil]

I am not sure of what you need exactly, so I suggest you look at this code and come back with questions if needed.

Here you have some ways to manipulate strings and pointers that should fit you needs.

Rgrds

Code: Select all

;
; ANSI2UNI
;
; Converts an ANSI string to a Unicode compatible string
;
; in  <=  ansi string
; out => unicode string pointer
;
ProcedureDLL.l ANSI2UNI(ansi.s) 
  size.l=MultiByteToWideChar_(#CP_ACP,0,ansi,-1,0,0) 
  Dim unicode.w(size) 
  MultiByteToWideChar_(#CP_ACP, 0, ansi, Len(ansi), unicode(), size) 
  ProcedureReturn @unicode()  
EndProcedure 

;
; UNI2ANSI
;
; Converts a Unicode string to an ANSI string
;
; in  <=  unicode string pointer
; out => ansi string
;
ProcedureDLL.s UNI2ANSI(*Unicode.l) 
  size.l = WideCharToMultiByte_(#CP_ACP, 0, *Unicode, -1, #Null, #Null, #Null, #Null) 
  ansi.s=Space(size) 
  WideCharToMultiByte_(#CP_ACP, 0, *Unicode, -1, @ansi, size, #Null, #Null) 
  ProcedureReturn ansi  
EndProcedure 

;
; FileToString
;
; Loads a full file in a single ANSI string
;
; in  <=  Filename
; out => Pointer to the string containing the file's content
;
ProcedureDLL.s FileToString(FileName.s) 
  Result.s = "" 
  If ReadFile(99, FileName) 
      LengthOfFile.l = Lof() 
      *Buffer = AllocateMemory(LengthOfFile) 
      ReadData(*Buffer, LengthOfFile) 
      CloseFile(99) 
      Result.s = PeekS(*Buffer) 
      FreeMemory(*Buffer) 
  EndIf 
  ProcedureReturn Result 
EndProcedure 

ProcedureDLL.l StringToPointer(String.s)
  ProcedureReturn @String
EndProcedure

; 
; test code 
; 
  Debug FileToString("C:\test.txt")
  *Pointer = ANSI2UNI("Ben ça alors, dis donc, si j'avais su.")
  Debug UNI2ANSI(*Pointer)
  String.s = "azertyqwertyqwertz"
  Debug StringToPointer(String)
  Debug @String

[Edwin Knoppert]

1) your calls use swapped names like uni2ansi but returns uni
2) VB seems to prefer ansi data (BSTR)

The example posted is used a lot..

[fweil]

post updated ... sorry for the mix ...

[neomancer]

I got a Syntax error! Protected lPSTR.l
[edit]
WORKS!!!!!!!!!!

your lovely! wow and its so simple!

[TeraByte]

Addict,

Thank you for your great VB to PB example. It is much appreciated and works perfect.

[swan]

Tell me that it didn't take U 8 years to figure out it worked ???