need to call managed code from unmanaged c++ code !

[=?Utf-8?B?UmF2aSBTaGFua2Fy?=]

Hi,

I have a requirement where I need to call methods written in VB.Net from a
C++ code. I have been going crazy reading various articles on the net w.r.t
interop and marshalling but an more confused now that before.

the signature I need to conform in the VB.Net DLL is
int MyAppInitFunc(i nt argc, char** argv)

To this extent I have tried the following
Public Function MyAppInitFunc(B yVal argc as integer, ByRef argv as string)
as Integer
Public Function MyAppInitFunc(B yVal argc as Int32, ByVal argv() as string)
as Int32

.... based on some posts I even tried
Public Function MyAppInitFunc(B yVal argc as Int32, ByVal argv as IntPtr) as
Int32

but have not been able to get anything to work.

Is there perhaps some reading I'm missing up on ?

Regards.

--
Ravi Shankar

[Michel Posseth [MCP]]

I do all my vb6 interop through COM , this works great

maybe this is an idea for you to ?

Regards

Michel

"Ravi Shankar" <sh*********@ne wsgroup.nospams chreef in bericht
news:4F******** *************** ***********@mic rosoft.com...

Hi,

I have a requirement where I need to call methods written in VB.Net from a
C++ code. I have been going crazy reading various articles on the net
w.r.t
interop and marshalling but an more confused now that before.

the signature I need to conform in the VB.Net DLL is
int MyAppInitFunc(i nt argc, char** argv)

To this extent I have tried the following
Public Function MyAppInitFunc(B yVal argc as integer, ByRef argv as string)
as Integer
Public Function MyAppInitFunc(B yVal argc as Int32, ByVal argv() as string)
as Int32

... based on some posts I even tried
Public Function MyAppInitFunc(B yVal argc as Int32, ByVal argv as IntPtr)
as
Int32

but have not been able to get anything to work.

Is there perhaps some reading I'm missing up on ?

Regards.

--
Ravi Shankar

[Mattias Sjögren]

>the signature I need to conform in the VB.Net DLL is

>int MyAppInitFunc(i nt argc, char** argv)

Does that mean the C++ caller expects such a function to be a staticly
exported entrypoint from the DLL? VB doesn't let you do that.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[=?Utf-8?B?UmF2aSBTaGFua2Fy?=]

Hello Michel,

Please explain.. I have made my project with "Register for COM Interop". I
have also done a regasm /tlb:.....

All my functions are ComVisible().

Since there is a difference in the VB.Net DLL's and classic Win32 DLL's,
I've even done the IL tweaking to ensure that my functions are being exported.

I can't figure out how to get Char** marshalled into my managed code ?

The combinations Ive tried are
1. <MarshalAs(Unma nagedType.SafeA rray, SafeArraySubTyp e:=VarEnum.VT_B STR)>
ByVal argv as string()

This gives me an error saying SafeArray of rank 11888 has been passed to a
method expecting an array of rank 1

2. <MarshalAs(Unma naged.LPArray)B yRef argv as string

This gives me an error saying cannot marshal 'parameter #2' : Invalid
managed/unmanaged type combination (string parameters and return types must
be paired with LPStr, LPWStr, LPTStr, BSTR, TBStr, VBByRefStr, or AnsiBStr).

and combiantions of the above with char()() instead of string() etc, etc.
x--
Ravi Shankar
"Michel Posseth [MCP]" wrote:

I do all my vb6 interop through COM , this works great

maybe this is an idea for you to ?

Regards

Michel

"Ravi Shankar" <sh*********@ne wsgroup.nospams chreef in bericht
news:4F******** *************** ***********@mic rosoft.com...

Hi,

I have a requirement where I need to call methods written in VB.Net from a
C++ code. I have been going crazy reading various articles on the net
w.r.t
interop and marshalling but an more confused now that before.

the signature I need to conform in the VB.Net DLL is
int MyAppInitFunc(i nt argc, char** argv)

To this extent I have tried the following
Public Function MyAppInitFunc(B yVal argc as integer, ByRef argv as string)
as Integer
Public Function MyAppInitFunc(B yVal argc as Int32, ByVal argv() as string)
as Int32

... based on some posts I even tried
Public Function MyAppInitFunc(B yVal argc as Int32, ByVal argv as IntPtr)
as
Int32

but have not been able to get anything to work.

Is there perhaps some reading I'm missing up on ?

Regards.

--
Ravi Shankar

[=?Utf-8?B?UmF2aSBTaGFua2Fy?=]

Hi Mattias,

I has to do some IL tweaking to get my functions exported. Now If I can get
definitions that would permit my variables to be marshalled properly to
unmanaged code, it'd work.
--
Ravi Shankar
"Mattias Sjögren" wrote:

the signature I need to conform in the VB.Net DLL is
int MyAppInitFunc(i nt argc, char** argv)

Does that mean the C++ caller expects such a function to be a staticly
exported entrypoint from the DLL? VB doesn't let you do that.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Mattias Sjögren]

>I has to do some IL tweaking to get my functions exported. Now If I can get

>definitions that would permit my variables to be marshalled properly to
unmanaged code, it'd work.

OK, assuming you get that part to work, I recommend that you go with
the third method signature you posted (with ByVal argv as IntPtr). You
also have to make sure the calling convention is correct.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[=?Utf-8?B?UmF2aSBTaGFua2Fy?=]

Ok so you're suggesting I try

<MarshalAs(Unma naged.LPArray)B yVal argv as IntPtr ?

I'll post the results a little later.

Regards.
--
Ravi Shankar
"Mattias Sjögren" wrote:

I has to do some IL tweaking to get my functions exported. Now If I can get
definitions that would permit my variables to be marshalled properly to
unmanaged code, it'd work.

OK, assuming you get that part to work, I recommend that you go with
the third method signature you posted (with ByVal argv as IntPtr). You
also have to make sure the calling convention is correct.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[Mattias Sjögren]

>Ok so you're suggesting I try

>
<MarshalAs(Unm anaged.LPArray) ByVal argv as IntPtr ?

You can remove the MarshalAs attribute, it has no effect on IntPtrs.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[=?Utf-8?B?UmF2aSBTaGFua2Fy?=]

Hi Mattias,

I tried what you've suggested and the program went into a non-terminable
state with continuous error pop-ups stating

Unhandled Exception at 0x008f213a in ....exe: 0xC0000005: Access violations
reading loactions 0x00000000

Which sound like a "null" pointer exception to me in a different package :)

Regards,
--
Ravi Shankar
"Mattias Sjögren" wrote:

Ok so you're suggesting I try

<MarshalAs(Unma naged.LPArray)B yVal argv as IntPtr ?

You can remove the MarshalAs attribute, it has no effect on IntPtrs.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.

[=?Utf-8?B?UmF2aSBTaGFua2Fy?=]

Any more recommendations ?
--
Ravi Shankar
"Mattias Sjögren" wrote:

Ok so you're suggesting I try

<MarshalAs(Unma naged.LPArray)B yVal argv as IntPtr ?

You can remove the MarshalAs attribute, it has no effect on IntPtrs.
Mattias

--
Mattias Sjögren [C# MVP] mattias @ mvps.org
http://www.msjogren.net/dotnet/ | http://www.dotnetinterop.com
Please reply only to the newsgroup.