Passing a C# callback function through Interop/pinvoke

Question

I am writing a C# application which uses Interop services to access functions in a native C++ DLL. I am already using about 10 different functions which are working.

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Answer 1

Can you try changing the Func delegate to

    public delegate void Func([In, MarshalAs(UnmanagedType.LPStr)] string arg1, [In, MarshalAs(UnmanagedType.LPStr)] string arg2);

And the SetFunc method to

[DllImport("lib", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.Winapi)]
public static extern int SetFunc(Func lpfn);