VC++ dll and VB

Can I export class from VC++ and use it in VB ?

If you write an ActiveX dll in C++ you can, yes. That is what ActiveX is good at...

HTH,
Duncan

-------------------------------------------------
Ex. Datis: Duncan Jones
Merrion Computing Ltd
http://www.merrioncomputing.com
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Once writting a VC++ dll, register the dll file. Now, move into your VB program and from Project->Properties option add a reference to the new created dll entry. Now, when you will create a variable you will find the class name in the autolist drop-down.

If it is raw C++(not MFC or ATL COM), no.

Software is like sex, it's better when it's free - Linus Torvalds
Software is like sex, it's better when I get paid for it. - me

You can sort out this in two ways.

If the dll is derived from automation class (IClassFactory) and if it has the necessary functions to register you can use it after registering. (regsvr32 …..)
The Necessary function to register the dll's are

1. RegisterServer
2. UnRegisterServer

The second way is if you developed the dll without
any automations and register functions
then you have to explicitly export the functions

for Example
int add(int a,int b) to export this function
you have to write it like this

extern "C" __declspec(dllexport) int __stdcall add(int a,int b)

place the dll in the local directory where vb
application resides or to the system directory.

In the VB you have to declare the function like this

Public Declare function Add lib "YourlibraryName" Alias "_add@8"(byval a as integer,byval b as integer)as integer

here Yourlibraryname is the name of .lib file which
will be created along with the Dll.
And alias is the Alias name of the function

To find the Alias name of the function

Goto

Microsoft Visual Studio6.0->Microsoft Visual Studio6.0 Tools->Depends

it will open an application where you have to open your dll.

But you have to do some manipulations to pass string-based arguments
for further clarifications mail to me

I have written Com obj to pass struct arrays from VC to VB.
here is the code
IDL looks like this....

typedef struct tagUSERPARAMETERS
{
[string] BSTR bstrUserName;
[string] BSTR bstrPassword;
} UPARAM;
[
object,
uuid(ABF81033-3F0E-48A5-9AEB-9364E689FD32),
dual,
helpstring("ISSystem Interface"),
pointer_default(unique)
]
interface ISSystem : IDispatch
{
[id(1), helpstring("method Func")] HRESULT Func([in,out] UPARAM *stUParam, [out,retval] int *nErrVal);
[id(2), helpstring("method Func2")] HRESULT Func2([in]long Id, [in,out]SAFEARRAY(UPARAM) *psaUserParam);
};

and the VB code is this to call the above Func2....

option Explicit
Dim a as new SSYSLib.SSystem
Dim st(2) as SSYSLib.tagUSERPARAMETERS

private Sub Command1_Click()
a.Func2 1, st
MsgBox st(0).bstrPassword + st(0).bstrUserName
End Sub




this works fine, But my q'tion is....

1). Above works fine when it is a early binded obj (as included in the Project References..).
how can i pass struct array to a late binded obj. That is the above obj created thru CreateObject,
and not included in the reference in the 'Project references'.

2) Also How can pass above struct array from a VC client thru 'DISPPARAMS' to 'Invoke' method, without including the header files ?. Or how can i pass structs dynamicaly ?

Please i need ur help
Thanks in advance

by
Ramanan

(I will not hesitate to rate your answers.)