expose c++-cli dll to c#

Question

I am generating a dll using c++-cli. The class in the dll looks like this:

ref class Locator

{
public:
Locator(int HP) : m_HP(HP) { } 
~Locator() 
{ } 
Dictionary<String^, array< Byte >^>^ Locate(Dictionary<String^, String^>^ imgParms) 
{ .....  }

private:
int m_HP;

How can I expose it to use it in c#? The class and the members are not being exposed in c#

If this were a "normal" C/C++ program, you'd use Interop. Since this is a C++-CLI (managed C++) program, you should already *have* assemblies. Just reference them in your C# client. PS: I'm honestly curious why anybody would want to use C++ CLI (in contrast to VB.Net or C# for .Net, or standard C++ for portability and efficiency)? It's always baffled me... — paulsm4, Jul 10 '12 at 20:05
paulsm4: Sometimes, it's a matter of having native libraries to interop with, and writing the right P/Invoke and ComImport magic can be more difficult than wrapping the whole shebang in a C++/CLI `ref class`. :) — Rytmis, Jul 10 '12 at 20:11
I have to use C/C++ because I am using OpenCV for image processing but I'll try the ref — fmvpsenior, Jul 10 '12 at 20:11
So I added ref to class locator and now it doesn't compile: error C2664: 'cvReleaseCapture' : cannot convert parameter 1 from 'cli::interior_ptr' to 'CvCapture **' 1> with 1> [ 1> Type=CvCapture * 1> ] 1> Cannot convert a managed type to an unmanaged type — fmvpsenior, Jul 10 '12 at 20:55

score 4 · Accepted Answer · answered Jul 10 '12 at 22:03

4

You need to use the public keyword to make managed types visible to consumers of the assembly. Try

public ref class Locator { ... };

answered Jul 10 '12 at 22:03

Ben Voigt

277,958
43
419
720

score 0 · Answer 2 · edited May 23 '17 at 12:14

0

A question I asked a few months ago, regarding a similar issue :

How to use a C callback from C#?

Here are a few extra hints in my answer about the problem :

Calling C++ DLL from C++ works, but not from C#

I read you're using OpenCV, do you know Emgu CV: OpenCV in .NET (C#, VB, C++ and more) ? :-)

edited May 23 '17 at 12:14

Community

1
1

answered Jul 10 '12 at 22:08

aybe

15,516
9
57
105

score -1 · Answer 3 · answered Jul 10 '12 at 20:02

C++/CLI generates standard .NET managed assembly. That's the whole point of C++/CLI => compile an existing C++ code into a managed assembly without rewriting it to a CLS language.

So simply reference this assembly as any other .NET assembly in your consuming project. And then consume:

var imgParms = new Dictionary<string, string> { { "foo", "bar" }, { "baz", "bazinga" } };
var locator = new Locator(123);
var result = locator.Locate(imgParams);
// TODO: do something with the result dictionary

expose c++-cli dll to c#

3 Answers3