Question

I have a C++ class I’d like to access from a C# application. I’ll need to access the constructor and a single member function. Currently the app accepts data in the form of stl::vectors but I can do some conversion if that’s not likely to work?

I’ve found a few articles online which describe how to call C++ DLLs and some others which describe how to make .dll projects for other purposes. I’m struggling to find a guide to creating them in Visual Studio 2008 for use in a C# app though (there seem to be a few for VS 6.0 but the majority of the options they specify don’t seem to appear in the 2008 version).

If anyone has a step-by-step guide or a fairly basic example to get going from, I’d be very grateful.

Answer 1

The easiest way to interoperate between C++ and C# is by using managed C++, or C++/CLI as it is called. In VisualStudio, create a new C++ project of type “CLR Class Library”. There is some new syntax for the parts that you want to make available to C#, but you can use regular C++ as usual.

In this example, I’m using std::vector<int> just to show that you can use standard types – however, in an actual application, I’d prefer to use the .NET types where possible (in this case a System::Collections::Generic::List<int>).

#pragma unmanaged
#include <vector>
#pragma managed

public ref class CppClass
{
public:
   CppClass() : vectorOfInts_(new std::vector<int>)
   {}

   // This is a finalizer, run when GC collects the managed object
   !CppClass()
   { delete vectorOfInts_; }

   void Add(int n)
   { vectorOfInts_->push_back(n); }

private:
    std::vector<int>* vectorOfInts_;
};

EDIT: Changed the class to hold the vector by pointer instead of by value.