Declare dll function error

[XonsArgi]

Hello guys. I'm having trouble tryin to declare a function from a dll, in a test case I'm not bein' able to use a function that i made using visual basic in a dll.
Error 453 gets on my way no matter what i do.


The code in the VBA on excel is:

Declare Function TestReturn Lib "[I](Path to dll folder)\JMSys.dll[/I]" () As Double

Sub teste()
    MsgBox TestReturn
End Sub

The code usin' in the dll is:

Public Module LinearAlgebra
    Public Function ModulusOfVector(ByRef x As Double()) As Double


        Dim sum As Double
        Dim i As Long


        For i = LBound(x) To UBound(x)
            sum = sum + x(i) ^ 2
        Next i


        Return sum ^ (0.5)


    End Function
    Public Function TestReturn(x As Double) As Double
        TestReturn = 3
    End Function
End Module

The code on Visual Basic works for sure cause I tested on other application created in VB

Any lights?

 

[Jaafar Tribak]

Try adding the Alias keyword as follows and see if it works

Declare Function TestReturn Lib "(Path to dll folder)\JMSys.dll" Alias "TestReturn" () As Double

 

[XonsArgi]

Try adding the Alias keyword as follows and see if it works

Declare Function TestReturn Lib "(Path to dll folder)\JMSys.dll" Alias "TestReturn" () As Double

I already tried that Jaafar, but VBA erases the alias when it has the same string as the function declared. Tryin another one won't work either.

 

[Jaafar Tribak]

Have you tried looking up the Actual function name syntax in Dependecy Walker (If you have Visual Studio)

 

[Jaafar Tribak]

I am not sure with which program you are creating the dll but in the past, I created dll functions in PoweBasic and ,on occasions, I experienced similar problems when calling the dll functions from VBA ... The solution was to define the export function in the dll with an Alias ... Something like this maybe :

Public FUNCTION TestReturn ALIAS "_TestReturn" () AS DOUBLE

Notice the underscore

 

[Kenneth Hobson]

Learning by example is why I created my simple mathlib routines created in vb.net here. https://app.box.com/s/65ekeevb6ol0qg7pld4n

While the example at wpuniverse.com uses late binding, early binding can be used in VBA as well. It also has more details on how I created it. It may be a pain to register for a one time use but it is free. VB.NET - 112, Create DLL

I also posted most of the WordPerfect post into this other Excel forum. How to call\use DLL via vba macro?

 

[Jaafar Tribak]

Hi Kenneth,

Isn't that for creating COM dlls as opposed to Standard Dlls like the dll that we are dealing with here ?

As you know, COM dlls are loaded with the New Keyword or the CreateObject function but they first need to be registered ... whereas standard dlls don't need prior registration and its export functions are called via the vb Declare statement

 

[Kenneth Hobson]

Right. I did not know that declaration was what was needed.

Of course one can not use early binding in PerfectScript so I thought it be worth use here.

 

[XonsArgi]

Is there a way that I can use functions and subs from a COM dll? As I know the only thing that I can manipulate from a COM dll is objects...

 

[Jaafar Tribak]

Is there a way that I can use functions and subs from a COM dll? As I know the only thing that I can manipulate from a COM dll is objects...

You can.

Create a Class in the COM dll and call the dll Subs and Functions via the dll Class Properties/Methods

Something along these lines :

Set oObjectInstance = CreateObject("ProgId.ClassName")
Call oObjectInstance.ClassMethod