Re: Dll function call problem - Same problem

[Fabian]

I have exactly the same problem. My c-code:

__declspec(dllexport) int intarg(int intArg1)
{
return intArg1;
}

My VB-code:
Declare Function intarg Lib "testdll.dll" (ByVal intArg1 As Integer) As Integer
Sub runtestdll()
Dim intTest As Integer
intTest = 5
intTest = intarg(intTest)
MsgBox intTest
End Sub

This gives the error "Bad DLL calling convention". If I however declare the
function as if it doesn't have any parameters it does not give me an error.
Like this:
Declare Function intarg Lib "testdll.dll" () As Integer
Sub runtestdll()
Dim intTest As Integer
intTest = intarg()
MsgBox intTest
End Sub

It seems that the parameter in the c function isn't exported or something?
Does anyone have any idea how to solve this?

Greateful for any help.

/Fabian Fischer

"Pete Mitchell" <pmitchel@attachegroup.com> wrote:
>
>I keep getting the runtime error '49' "Bad DLL calling convention" error
message
>
>when calling a function in a dll from my VB program.
>It's C syntax is:
>long Julian_Date(char *szDate)
>
>Here is my Declaration in the General Decs of a form:
>Private Declare Function Julian_Date Lib "d:\Chariotts\qengine.dll" (ByVal
>
>sDate As String) As Long
>
>Here is the call to the function from a button click event:
>Private Sub Command1_Click()
> Dim retval As Long
> Dim sDate As String
>
> sDate = "19990625"
> retval = Julian_Date(sDate)
>
>End Sub
>
>I have also tried changing the function declaration to pass the parameter
>ByRef with the same result.
>
>I have successfully called this function from Visual FoxPro so I figured
>
>that the function is exposed and available.
>
>What am I doing wrong ????
>
>Thanks in advance.
>

[Fabian]

I have exactly the same problem. My c-code:

__declspec(dllexport) int intarg(int intArg1)
{
return intArg1;
}

My VB-code:
Declare Function intarg Lib "testdll.dll" (ByVal intArg1 As Integer) As Integer
Sub runtestdll()
Dim intTest As Integer
intTest = 5
intTest = intarg(intTest)
MsgBox intTest
End Sub

This gives the error "Bad DLL calling convention". If I however declare the
function as if it doesn't have any parameters it does not give me an error.
Like this:
Declare Function intarg Lib "testdll.dll" () As Integer
Sub runtestdll()
Dim intTest As Integer
intTest = intarg()
MsgBox intTest
End Sub

It seems that the parameter in the c function isn't exported or something?
Does anyone have any idea how to solve this?

Greateful for any help.

/Fabian Fischer

"Pete Mitchell" <pmitchel@attachegroup.com> wrote:
>
>I keep getting the runtime error '49' "Bad DLL calling convention" error
message
>
>when calling a function in a dll from my VB program.
>It's C syntax is:
>long Julian_Date(char *szDate)
>
>Here is my Declaration in the General Decs of a form:
>Private Declare Function Julian_Date Lib "d:\Chariotts\qengine.dll" (ByVal
>
>sDate As String) As Long
>
>Here is the call to the function from a button click event:
>Private Sub Command1_Click()
> Dim retval As Long
> Dim sDate As String
>
> sDate = "19990625"
> retval = Julian_Date(sDate)
>
>End Sub
>
>I have also tried changing the function declaration to pass the parameter
>ByRef with the same result.
>
>I have successfully called this function from Visual FoxPro so I figured
>
>that the function is exposed and available.
>
>What am I doing wrong ????
>
>Thanks in advance.
>

[Craig Clearman]

Fabian,

>It seems that the parameter in the c function isn't exported or something?
>Does anyone have any idea how to solve this?

You have to use Standard Calling conventions, not C calling
conventions.

Get rid of the __declspec(dllexport), and add __stdcall

Then, you'll have to add a .DEF module and declare the function inside
of that module.

Everything should work fine then.

Ciao, Craig

[Craig Clearman]

Fabian,

>It seems that the parameter in the c function isn't exported or something?
>Does anyone have any idea how to solve this?

You have to use Standard Calling conventions, not C calling
conventions.

Get rid of the __declspec(dllexport), and add __stdcall

Then, you'll have to add a .DEF module and declare the function inside
of that module.

Everything should work fine then.

Ciao, Craig

[ken guest]

Yep, consider __declspec(dllexport) as evil.
The dll function will work but you'll get error 49 (bad convention) when
it exits. You should always use the _stdcall /EXPORT combination for functions
in the dll that you want to call from VB.
I don't know if this affects programs written in other languages calling
those functions.


Ken


Craig Clearman <chclear@nospam.please> wrote:
>Fabian,
>
>>It seems that the parameter in the c function isn't exported or something?
>>Does anyone have any idea how to solve this?
>
>You have to use Standard Calling conventions, not C calling
>conventions.
>
>Get rid of the __declspec(dllexport), and add __stdcall
>
>Then, you'll have to add a .DEF module and declare the function inside
>of that module.
>
>Everything should work fine then.
>
>Ciao, Craig
>

[ken guest]

Yep, consider __declspec(dllexport) as evil.
The dll function will work but you'll get error 49 (bad convention) when
it exits. You should always use the _stdcall /EXPORT combination for functions
in the dll that you want to call from VB.
I don't know if this affects programs written in other languages calling
those functions.


Ken


Craig Clearman <chclear@nospam.please> wrote:
>Fabian,
>
>>It seems that the parameter in the c function isn't exported or something?
>>Does anyone have any idea how to solve this?
>
>You have to use Standard Calling conventions, not C calling
>conventions.
>
>Get rid of the __declspec(dllexport), and add __stdcall
>
>Then, you'll have to add a .DEF module and declare the function inside
>of that module.
>
>Everything should work fine then.
>
>Ciao, Craig
>

[Mattias Sjögren]

Ken,

>Yep, consider __declspec(dllexport) as evil.

It's _cdecl (or rather any calling convention other than _stdcall)
that is "evil", not __declspec(dllexport). You *can* use
__declspec(dllexport) and still call the function from VB, if you
correctly combine it with _stdcall, but the name of the exported
function will be mangled. Using a DEF file instead gives you more
control over the name and/or the ordinal of the exported function.


Mattias

____________________________________________
Mattias Sjögren - mattiass @ hem.passagen.se

[Mattias Sjögren]

Ken,

>Yep, consider __declspec(dllexport) as evil.

It's _cdecl (or rather any calling convention other than _stdcall)
that is "evil", not __declspec(dllexport). You *can* use
__declspec(dllexport) and still call the function from VB, if you
correctly combine it with _stdcall, but the name of the exported
function will be mangled. Using a DEF file instead gives you more
control over the name and/or the ordinal of the exported function.


Mattias

____________________________________________
Mattias Sjögren - mattiass @ hem.passagen.se