What exactly gets returned with extern(C) export string func() ?

[frame]

On Wednesday, 16 June 2021 at 02:46:36 UTC, cc wrote:

> I can't seem to get it to work as a return type, but 
> interestingly it does work as an out/pass by ref parameter.

Probably for returning the struct it needs some allocation 
directive in C# but I'm not sure. Maybe C# also tries something 
to do with the IntPtr. It may work if you use a struct on the DLL 
side too and convert any specific things like pointers to simple 
integers instead.

The out keyword however basically is just a pointer to the 
struct, so reading directly from the memory offset from the DLL 
works instead.

As long the GC sees the data alive - .(i)dup doesn't protect your 
memory here. The data could be collected by the GC anytime the 
function call goes out of scope.