Calling a C# function from unmanaged c++ (via a managed wrapper)

Question

I have C++ source & headers for a set of libraries which I need to call from a C# application. I've created a managed C++ wrapper around the functions I need and am able to call them from C# marshalling the data backwards and forwards.

Now the hard part..

My unmanaged C++ library generates status messages as it runs and I'd like to be able to display these from the calling C# application. My current thinking goes like this:

I'd like the unmanaged C++ library code to call a function in my C# code that I pass to the managed wrapper as I create it. I've found a few tutorials on Code Project but the syntax seem to be out of date.

If anyone has some sample code or could point me in the direction of a good tutorial that would be great.

Thanks in advance for any help.

Answer 1

You can pass a .NET delegate to a C++/CLI function that takes a pointer to a function with "matching" arguments.

Caveats

1. The pointer-to-function must be STDCALL calling conventions
2. If the delegate is a member of an object, this pointer to function will not count as a reference to keep the object alive. You have to maintain a reference to the object during the time that the callback is held

Since you think your examples are out of date, I am going to assume you are using the new syntax of C++/CLI. Here is a CodeProject with an example of how to do that

http://www.codeproject.com/KB/mcpp/FuncPtrDelegate.aspx