I have a C++ module which takes and returns parameters as (one and two D)
arrays of int and double.

I want to call this from c#, but I'm concerned about the memory
implications.  THe data items in question represent a sparse array which
may have many millions of entries.

The impression I have from the docs is that marshalling an array from clr
to C++ requires (at best) a bit copy.  This would effectively double the
amount of memory I would need which could be a serious problem.

Am I correct that there is a memory copy and is there any way of getting
round this?

Iain