Question

What is the best online guide/tutorial to start with interop using C# and C++/CLI ? I’m looking for a good guide in passing structures made in C# to C++/CLI. Many of the tutorials I have seen do not cover passing custom structures made in C# to C++/CLI.
Any suggestions ?

Thanks.

Answer 1

The reason you don’t find many tutorials is that there is really nothing to it. You pass the managed structure from C# to C++/CLI the same way as you would to another C# class/method

say you had structure in C#:

public struct TheStruct
{
  public int i;
  public String str;
}

You would write a method in C++/CLI that looked like this:

// *.h
void PassStruct(TheStruct ^myStruct); 


// *.cpp
void classnamegoeshere::PassStruct(TheStruct ^myStruct)
{
   int j = myStrict->i;
   String ^localStr = myStruct->str;
}

So, a couple of notes…

1. you need to make sure you put the using statement in your C++/CLI
   code to get your C# reference
2. Include the C# assembly (that defines the struct) in the C++/CLI reference list)
3. Managed objects always use the ^ pointer notation (vs. *)
4. To use methods or member use standard pointer notation ( -> )

5. You need to be careful not to create circular references, so you may want to have TheStruct defined in C++/CLI in which case it would
   look like:

   public ref struct TheStruct
   {
   public:
   int i;
   String ^str;
   }

Easy enought?