Other Objects

[ryan]

I'm wonder how a MSVC++ DLL might interact with other objects on the system. In VB you can create the object like so and use it:

Dim MyObject
Set MyObject = Server.CreateObject("x.x&quot

How would I could I access an object like this from C?

RGK

 

[chiph]

Straight C -- Do a LoadLibrary() followed by GetProcAddress() calls for each of the exported functions you want to use. This would be "late bound"

Or...
Link the DLL statically into your project. This would be "early bound".

Chip H.

 

[Cagliostro]

Hi
chiph, it is a COM program.
Ryank,
------------------------------------
GUID guid;
IDispatch* pDisp;
HRESULT hr;
hr=CLSIDFromProgID(L"x.x",&guid);
hr=CoCreateInstance(guid,NULL,CLSCTX_INPROC_SERVER,
DDI_IDispatch,&pDisp);
//do something
pDisp->Release();
////the interface pDisp is an analog of you object in VB.
-----------------------------------
Also a better way is to obtain at the first the interface IUnknown:
GUID guid;
IDispatch* pDisp;
IUnknown* pUnk;
HRESULT hr;
hr=CLSIDFromProgID(L"x.x",&guid);
hr=CoCreateInstance(guid,NULL,CLSCTX_INPROC_SERVER,
DDI_IUnknown,&pUnk);
hr=pUnk->QueryInterface(IID_IDispatch,&pDisp);
//do something
pDisp->Release();
pUnk->Release();
With interface IUnknown you can query all interfaces what the object expose.
----------------------------------
you should check on errors the hresult (hr) after each function executed.
if(FAILED(hr))
{
....
}
or
if(SUCCEDED(hr))
{
}
-------------
To begin working with COM you must call
hresult=OleInitialize(NULL);
or CoInitialize(...).
after end of COM programming call
OleUninitialize().

 

[Cagliostro]

There is a DDI_I..., please replace with IID_I...
It is my mistake.

 

[palbano]

Using the ATL smart pointers and the '#import' statement to generate the template typedefs is WAY easier and safer than interfacing directly with COM API's.

"But, that's just my opinion... I could be wrong".
-pete