从C ++ DLL访问C＃静态类

Question

I've been tasked with writing a new interface to a legacy C++ DLL I don't have the source code for, which - for reasons beyond me - accesses a global class in the legacy application directly.

From the application, it's something like:

extern Interface *App;

...

Interface App*;   //  A pointer to our interface class.

Then, from the legacy DLL:

if( App->GetStatus() ) return false;

The Interface class that App refers to is quite trivial to rewrite in C#, but how can I make it the equivalent of extern so that the legacy C++ DLL can access it?

Thanks!

Answer 1

You could try using Robert Giesecke's " UnmanagedExports " nuget package to achieve this functionality like so:

class Test
{
    [DllExport("add", CallingConvention = CallingConvention.Cdecl)]
    public static int TestExport(int left, int right)
    {
       return left + right;
    } 
}

However :

a) I believe this only works for methods, not classes and

b) the reason there isn't a native way to export a DLL in C# is because that the calling application must have the .NET framework loaded in order to access that entry point. This also applies to the UnmanagedExports nuget package that I linked to above.

You can hack your way around this by getting your C++ app to load mono before calling the C# app, but it doesn't sound like this is possible in your case.

(Also, UnmanagedExports will only work if you explicitly set a build target in your project's properties - eg. x86)