Calling C# from C++, Reverse P/Invoke, Mixed Mode DLLs and C++/CLI

Question

As I understand it I can use reverse P/Invoke to call C# from C++. Reverse P/Invoke is simply a case of:

1. Create you managed (c#) class.
2. Create a c++/

Answer 1

Note, you can also do a IL roundtrip of the C# dll and export static methods, which work basically the same as the exports in C++/CLI. However, this is always a post-compile step, and it does have some caveats (which your C++/CLI export have too, btw.).

You can ILDASM both the C# and the C++/CLI DLLs to see how exports are don; it is something like this (from a sample on the net):

// unmexports.il
// Compile with : ilasm unmexports.il /dll
assembly extern mscorlib {}
..assembly UnmExports {}
..module UnmExports.dll
// This flag is important
..corflags 0x00000002
// This instructs the CLR to create a marshaling thunk for the unmanaged caller
..vtfixup [1] int32 fromunmanaged at VT_01
..data VT_01 = int32(0)
..method public static void foo()
{
..vtentry 1:1
..export [1] as foo
ldstr "Hello from managed world"
call void [mscorlib]System.Console::WriteLine(string)
ret
}