Re: How to pass strings from VC++.exe to C#.dll

From:

raghudr@gmail.com

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 17 Sep 2008 06:12:39 -0700 (PDT)

Message-ID:

<526599dc-e8b0-4ac7-8e5a-4c9fb8b83db3@k7g2000hsd.googlegroups.com>

On Sep 17, 6:01 pm, ragh...@gmail.com wrote:

On Sep 16, 10:03 pm, "Giovanni Dicanio"

<giovanniDOTdica...@REMOVEMEgmail.com> wrote:

<ragh...@gmail.com> ha scritto nel messaggionews:a70d6395-1bef-43db-93d=

d-cdbad0e5d24a@x35g2000hsb.googlegroups.com...

I have to pass a string from VC++.exe to C#.dll
void main()
{
CoInitialize(NULL);
MyInterop::IMyDotNetInterfacePtr pDotNetCOMPtr;
WCHAR str[] = _T("C:\\Debugging\\MyInterop\\MyInterop\\bin\\=

Debug\

\rag.xml");

If you are passing a WCHAR string, better making it explicit with L"...=

instead of _T():

WCHAR str[] = L"C:\\Debugging\....";

HRESULT hRes =
pDotNetCOMPtr.CreateInstance(MyInterop::CLSID_MyDotNetClass);

if (hRes == S_OK)
{
pDotNetCOMPtr->ShowDialog (str);

Have you stepped in this code using a debugger?
Is the above pDotNetCOMPtr->ShowDialog(str) statement executed?
Would it be possible that hRes is not a success code, so the call to
ShowDialog() method is not executed?

Moreover, would it be possible to you to check failure and success usin=

proper COM helper macros like FAILED() and SUCCEEDED() ?
e.g.

if ( SUCCEEDED( hRes ) )
... OK

Moreover, usually strings in COM are passed using BSTR (which is basica=

lly a

WCHAR Unicode string with string length prefixed).
So, should you pass a BSTR instead of a simple WCHAR* to the COM interf=

ace?

HTH,
Giovanni- Hide quoted text -

- Show quoted text -

Thanks for reply Giovanni Dicanio
I solved it this way

In C# .dll i changed the functon definition to

public string ShowDialog(StringBuilder str)
{

      Then string myString2 = str.ToString(); //It worked fine in VC
++.exe the string type is WCHAR

}

Now i have to return a string from C#.dll which is a COM component and
receive it in VC++.exe.I am not sure on how to do this

i changed the syntax to

public string ShowDialog(StringBuilder str)
{

   string dest ="C:\\RAGHU\\rag.xml";
  return dest;
}

In Vc++ .exe

int _tmain(int argc, _TCHAR* argv[])
{
    CoInitialize(NULL);
    MyInterop::IMyDotNetInterfacePtr pDotNetCOMPtr;
                WCHAR str[] = _T("C:\\cellOpcServer\
\195CellOpcServerConf_00.xml");
    HRESULT hRes =
pDotNetCOMPtr.CreateInstance(MyInterop::CLSID_MyDotNetClass);
    WCHAR pretval;

    if (SUCCEEDED(hRes))
    {
        pretval = pDotNetCOMPtr->ShowDialog(str);//giving error in this
statement
    }

    CoUninitialize ();
    return 0;
}

I am not sure how to return string from C#.dll to VC++.exe .I am new
to comprogramming can u please tell me how to fix this

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