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muchado

Any idea why DLLOpen returns something other than a handle?

4 posts in this topic

I have written a script that I want to use to call a DLL. However, when I call it using DLLOpen, it returns an integer rather than a handle. This would make sense if it was a "-1" error code, but instead it is a "1".

If FileExists ( @SystemDir & "\MyDLL.dll" ) Then
    ConsoleWrite ( "DLL exists and is located here: " & @SystemDir  & @CRLF )
Else
    ConsoleWrite ( "DLL not found in " & @SystemDir & @CRLF )
    Exit
EndIf

Global $hDll = DllOpen(@SystemDir & "\MyDLL.dll")
ConsoleWrite ( "DLLOpen MyDLL returns " & $hDLL & @CRLF )
If $hDll = -1 Then Exit MsgBox(0, "", "Failed to open MyDLL.dll")
Global $aDLL = DllCall($hDLL, "BOOL", "Output", "str", "AdSec_Driver", "str", "ETABS" )
ConsoleWrite("!" & @error & "-" & @extended & @CRLF)

ConsoleWrite ( "MyDLL returns data of type " & VarGetType( $aDLL) & @CRLF )

_ArrayDisplay($aDLL)
MsgBox(0, "", $aDLL[0])

DllClose($hDll)

When I run this I get the following output on the console:

DLL exists and is located here: C:\Windows\system32
DLLOpen MyDLL returns 1
!3-0
MyDLL returns data of type Int32
"C:\Users\andrew.mole\Documents\autoit\AdSec_Driver\trunk\AdSec_Driver.au3" (197) : ==> Subscript used on non-accessible variable.:
MsgBox(0, "", $aDLL[0])
MsgBox(0, "", $aDLL^ ERROR

Any idea why this is?

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Look at the @error set by DllCall (3) the documentation says that this means ""function" not found in the DLL file,".

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DllOpen never returns a real valid handle. AutoIt hides it for you and you just get an identifier from DllOpen. But you can use it like a handle within the AutoIt functions.

As DatMCEyeBall said, there is another problem: The function name is not found in the DLL. Use a tool like dependency walker or DLLEXP to see what is the right name. I think your function name got decorated by the compiler.


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build bigger and better idiot-proof programs, and the Universe
trying to produce bigger and better idiots.
So far, the Universe is winning.

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