Problem with Array from C# to COM

[mupe]

Hi,

i have a problem with a Type Library, which is written in C++.
I am developing an application in C#.NET and have to use functions from
this COM-Type Library. When I use these functions in the "old" VB it
works but not in .NET. I think it is a problem with marshalling but I
could not find a solution yet.

First I included the Type Library in VS.NET 2003. Other functions of
the TL work so the reference to the Lib must be correct.

Here the piece of code in C#.NET:

app = new nwApplication() ;
int[] id = new int[2];
id[0] = 1;
id[1] = 2;

broadcast = app.get_broadca st(id);

app is an Application-Object of the Library. The array id has two
numbers. The get_broadcast method needs this array as parameter and
returns a broadcast-object.

Here is the PROBLEM. I seems that the get_broadcast method does not get
the content of the array correctly.

I tried it in VB like this:

Dim app, broadcast, id
id = Array(1,2)
Set app = CreateObject("N wLib.nwApplicat ion")
Set broadcast = app.get_broadca st(id)

This works correctly.

When I look for the get_broadcast message in the object browser the
definition is like this:
nwApplication.g et_broadcast(ob ject)

When i compile my project, VS.NET creates a Interop.nw.dll. I
disassembled it to IL and looked for the definitions of the method. It
was like this:

......... get_broadcast(o bject marshal( struct) Value)....

Is it possible that the array in C# is not correctly marshalled?

Has anyone an idea where the problem could be? Thanks very much!

Peter

[Clive Dixon]

Re: Problem with Array from C# to COM

It sounds likely that the array is not being correctly marshalled. For the
C# code you are using, you may have to modify your interop assembly usiing
ildasm, a text editor, and ilasm to compile back. The marshalling in the IL
may have to be changed to something like

marshal(int32[])

or even

marshal(safearr ay int32)

However I don't know what the method definition looks like in your TLB. The
marshalling specified in the interop dll may well be correct but what you
are trying to do in your C# is incorrect. (I don't know what the VB Array
operation does.)

"mupe" <p.mueller@eise nmann.de> wrote in message
news:1138026398 .937069.58280@f 14g2000cwb.goog legroups.com...[color=blue]
> Hi,
>
> i have a problem with a Type Library, which is written in C++.
> I am developing an application in C#.NET and have to use functions from
> this COM-Type Library. When I use these functions in the "old" VB it
> works but not in .NET. I think it is a problem with marshalling but I
> could not find a solution yet.
>
> First I included the Type Library in VS.NET 2003. Other functions of
> the TL work so the reference to the Lib must be correct.
>
> Here the piece of code in C#.NET:
>
> app = new nwApplication() ;
> int[] id = new int[2];
> id[0] = 1;
> id[1] = 2;
>
> broadcast = app.get_broadca st(id);
>
> app is an Application-Object of the Library. The array id has two
> numbers. The get_broadcast method needs this array as parameter and
> returns a broadcast-object.
>
> Here is the PROBLEM. I seems that the get_broadcast method does not get
> the content of the array correctly.
>
> I tried it in VB like this:
>
> Dim app, broadcast, id
> id = Array(1,2)
> Set app = CreateObject("N wLib.nwApplicat ion")
> Set broadcast = app.get_broadca st(id)
>
> This works correctly.
>
> When I look for the get_broadcast message in the object browser the
> definition is like this:
> nwApplication.g et_broadcast(ob ject)
>
> When i compile my project, VS.NET creates a Interop.nw.dll. I
> disassembled it to IL and looked for the definitions of the method. It
> was like this:
>
> ......... get_broadcast(o bject marshal( struct) Value)....
>
> Is it possible that the array in C# is not correctly marshalled?
>
> Has anyone an idea where the problem could be? Thanks very much!
>
> Peter
>[/color]

[Clive Dixon]

Re: Problem with Array from C# to COM

....I'm also slightly surprised that the IL doesn't mark the parameter with
[in] (unless you missed that out).

Can you supply the method signature in the type library and the full method
definition in IL?

"mupe" <p.mueller@eise nmann.de> wrote in message
news:1138026398 .937069.58280@f 14g2000cwb.goog legroups.com...[color=blue]
> Hi,
>
> i have a problem with a Type Library, which is written in C++.
> I am developing an application in C#.NET and have to use functions from
> this COM-Type Library. When I use these functions in the "old" VB it
> works but not in .NET. I think it is a problem with marshalling but I
> could not find a solution yet.
>
> First I included the Type Library in VS.NET 2003. Other functions of
> the TL work so the reference to the Lib must be correct.
>
> Here the piece of code in C#.NET:
>
> app = new nwApplication() ;
> int[] id = new int[2];
> id[0] = 1;
> id[1] = 2;
>
> broadcast = app.get_broadca st(id);
>
> app is an Application-Object of the Library. The array id has two
> numbers. The get_broadcast method needs this array as parameter and
> returns a broadcast-object.
>
> Here is the PROBLEM. I seems that the get_broadcast method does not get
> the content of the array correctly.
>
> I tried it in VB like this:
>
> Dim app, broadcast, id
> id = Array(1,2)
> Set app = CreateObject("N wLib.nwApplicat ion")
> Set broadcast = app.get_broadca st(id)
>
> This works correctly.
>
> When I look for the get_broadcast message in the object browser the
> definition is like this:
> nwApplication.g et_broadcast(ob ject)
>
> When i compile my project, VS.NET creates a Interop.nw.dll. I
> disassembled it to IL and looked for the definitions of the method. It
> was like this:
>
> ......... get_broadcast(o bject marshal( struct) Value)....
>
> Is it possible that the array in C# is not correctly marshalled?
>
> Has anyone an idea where the problem could be? Thanks very much!
>
> Peter
>[/color]

[mupe]

Re: Problem with Array from C# to COM

Hi,

yes i will post the code tomorrow when I am back in office.

I already disassembled the assembly to IL and then I tried to recompile
it but that did not work.
So I disassembled it and recompiled it without any changes but then I
got an error message
that an entry point was not found and the dll was not created. I will
post the exact error message tomorrow.

Thanks so long.

[Vlad P]

RE: Problem with Array from C# to COM

I don’t know what is the problem but as far as you received the
[nwApplication.g et_broadcast(ob ject)]
Object that means you receive the address of the array object and you just
need to work out the indexes/values of your object?

If I missed your point ignore the message.

Vlad P

"mupe" wrote:
[color=blue]
> Hi,
>
> i have a problem with a Type Library, which is written in C++.
> I am developing an application in C#.NET and have to use functions from
> this COM-Type Library. When I use these functions in the "old" VB it
> works but not in .NET. I think it is a problem with marshalling but I
> could not find a solution yet.
>
> First I included the Type Library in VS.NET 2003. Other functions of
> the TL work so the reference to the Lib must be correct.
>
> Here the piece of code in C#.NET:
>
> app = new nwApplication() ;
> int[] id = new int[2];
> id[0] = 1;
> id[1] = 2;
>
> broadcast = app.get_broadca st(id);
>
> app is an Application-Object of the Library. The array id has two
> numbers. The get_broadcast method needs this array as parameter and
> returns a broadcast-object.
>
> Here is the PROBLEM. I seems that the get_broadcast method does not get
> the content of the array correctly.
>
> I tried it in VB like this:
>
> Dim app, broadcast, id
> id = Array(1,2)
> Set app = CreateObject("N wLib.nwApplicat ion")
> Set broadcast = app.get_broadca st(id)
>
> This works correctly.
>
> When I look for the get_broadcast message in the object browser the
> definition is like this:
> nwApplication.g et_broadcast(ob ject)
>
> When i compile my project, VS.NET creates a Interop.nw.dll. I
> disassembled it to IL and looked for the definitions of the method. It
> was like this:
>
> ......... get_broadcast(o bject marshal( struct) Value)....
>
> Is it possible that the array in C# is not correctly marshalled?
>
> Has anyone an idea where the problem could be? Thanks very much!
>
> Peter
>
>[/color]

[mupe]

Re: Problem with Array from C# to COM

@Vlad P: No, the object I get back from the method needs the value of
the array for internal use. And because of the object´s behaviour I
think that it does not get the value of the array correctly.

@Clive Dixon: Recompilation with ilasm now works. I forgot some options
yesterday. Here I have the pieces of IL code I found in the nw.il after
disassembling it from Interop.Nw.dll. The names of methods could be
different to those I posted yesterday but nwBroadcast is the object I
get back from the method get_nwBroadcast ().

.method public hidebysig newslot specialname virtual
instance class nwLib.nwBroadca st
marshal( interface)
get_nwBroadcast (object marshal( struct) Value) runtime
managed internalcall
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
.override nwLib.InwApplic ation::get_nwBr oadcast
} // end of method nwApplicationCl ass::get_nwBroa dcast

....

.property class nwLib.nwBroadca st
nwBroadcast(obj ect)
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
.get instance class nwLib.nwBroadca st
nwLib.nwApplica tionClass::get_ nwBroadcast(obj ect)
} // end of property nwApplicationCl ass::nwBroadcas t

....

.method public hidebysig newslot specialname abstract virtual
instance class nwLib.nwBroadca st
marshal( interface)
get_nwBroadcast (object marshal( struct) Value) runtime
managed internalcall
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
} // end of method InwApplication: :get_nwBroadcas t

....

.property class nwLib.nwBroadca st
nwBroadcast(obj ect)
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
.get instance class nwLib.nwBroadca st
nwLib.InwApplic ation::get_nwBr oadcast(object)
} // end of property InwApplication: :nwBroadcast

Thats all I found to this method.

In another method I get back an object which I cast to System.Array in
my C#-Code. I found in IL code that this is also marshalled as struct.
But that works without any problems?! Here the code:

.method public hidebysig newslot abstract virtual
instance object
marshal( struct)
ScanNet([in] int32 lngStartID,
[in] int32 lngEndID) runtime managed internalcall
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 03 00 00 00 00 00 )
} // end of method InwNetwork::Sca nNet


I also tried marshal( int32[]) like you told me yesterday but that did
not work. I got an error message: "parameter #1 can not be marshalled.
Invalid managed/unmanaged type combination (the object class has to be
combined with Interface, IUnknown, IDispatch, AsAny or Struct."

I hope you can help me with the code above. Thanks in advance!

Peter

[mupe]

Re: Problem with Array from C# to COM

I viewed the Type Lib in the C++ TypeLib Viewer and there it looked
likes this:

[id(0x0000000f), propget, helpstring("pro perty nwBroadcast")]
HRESULT nwBroadcast(
VARIANT Value,
[out, retval] InwBroadcast** pVal);

Since my last entry I tried more things but nothing works....

[Clive Dixon]

Re: Problem with Array from C# to COM

Seems odd that the System.Array to VARIANT (IL 'struct') marshalling happens
one way but not the other.

Next up, I would suggest you try manually marshalling the array to VARIANT
before you pass it, using Marshal.GetNati veVariantForObj ect.

You will first need to allocate some memory for the out VARIANT using
Marshal.AllocCo TaskMem. I don't immediately see a way of allocating the
exact size for a VARIANT in C# so you'll probably have to try giving it a
"sufficient ly large" amount (from memory a VARIANT is 16 bytes, but don't
quote me on that).

"mupe" <p.mueller@eise nmann.de> wrote in message
news:1138095798 .732965.6420@o1 3g2000cwo.googl egroups.com...
@Vlad P: No, the object I get back from the method needs the value of
the array for internal use. And because of the object´s behaviour I
think that it does not get the value of the array correctly.

@Clive Dixon: Recompilation with ilasm now works. I forgot some options
yesterday. Here I have the pieces of IL code I found in the nw.il after
disassembling it from Interop.Nw.dll. The names of methods could be
different to those I posted yesterday but nwBroadcast is the object I
get back from the method get_nwBroadcast ().

.method public hidebysig newslot specialname virtual
instance class nwLib.nwBroadca st
marshal( interface)
get_nwBroadcast (object marshal( struct) Value) runtime
managed internalcall
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
.override nwLib.InwApplic ation::get_nwBr oadcast
} // end of method nwApplicationCl ass::get_nwBroa dcast

....

.property class nwLib.nwBroadca st
nwBroadcast(obj ect)
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
.get instance class nwLib.nwBroadca st
nwLib.nwApplica tionClass::get_ nwBroadcast(obj ect)
} // end of property nwApplicationCl ass::nwBroadcas t

....

.method public hidebysig newslot specialname abstract virtual
instance class nwLib.nwBroadca st
marshal( interface)
get_nwBroadcast (object marshal( struct) Value) runtime
managed internalcall
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
} // end of method InwApplication: :get_nwBroadcas t

....

.property class nwLib.nwBroadca st
nwBroadcast(obj ect)
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 0F 00 00 00 00 00 )
.get instance class nwLib.nwBroadca st
nwLib.InwApplic ation::get_nwBr oadcast(object)
} // end of property InwApplication: :nwBroadcast

Thats all I found to this method.

In another method I get back an object which I cast to System.Array in
my C#-Code. I found in IL code that this is also marshalled as struct.
But that works without any problems?! Here the code:

.method public hidebysig newslot abstract virtual
instance object
marshal( struct)
ScanNet([in] int32 lngStartID,
[in] int32 lngEndID) runtime managed internalcall
{
.custom instance void
[mscorlib]System.Runtime. InteropServices .DispIdAttribut e::.ctor(int32)
= ( 01 00 03 00 00 00 00 00 )
} // end of method InwNetwork::Sca nNet


I also tried marshal( int32[]) like you told me yesterday but that did
not work. I got an error message: "parameter #1 can not be marshalled.
Invalid managed/unmanaged type combination (the object class has to be
combined with Interface, IUnknown, IDispatch, AsAny or Struct."

I hope you can help me with the code above. Thanks in advance!

Peter

[mupe]

Re: Problem with Array from C# to COM

This is the code I tried:

IntPtr mem;

int[] appId = new int[2];
appId[0] = 1;
appId[1] = 2;

mem = Marshal.AllocCo TaskMem(64); // also tried 32.....

Marshal.GetNati veVariantForObj ect(appId, mem);

nwBroad = nwApp.get_nwBro adcast(mem);

It does not work. It has the same effect like using appId directly as
parameter......

Do I have to edit the IL code for this too??

Thanks.

[mupe]

Re: Problem with Array from C# to COM

Today I tried something new. I wrote a VB6-DLL as "debug layer" which
gets the array as parameter. This dll hands the array over to the
getBroadcast method (in VB6 the whole thing works, so I chose VB6). I
returned the array from the dll back to my c# application and I got the
array with the correct numbers in it... but...
....if I hand over the array without doing anything other it does not
work.
If I define a new array in the dll and copy the content of the array I
get as parameter into that new array, it works! So it has something to
do with marshaling. The numbers in the parameter array are correct. If
I view them in debug mode they are of type Variant/Integer.
The new array i define is also Variant/Integer so I do not see any
difference?!?