Marshalling C# Jagged Array to C++

Question

I'm trying to marshal a 2D C# jagged array (double[][] jaggedArray) to a C++ dll where i've specified the receiving variable to be a double**.

However, i'm getting the message:

There is no marshaling support for nested arrays.

Short of flattening the jagged array is there a way to use jagged arrays from C# in a C++ dll?

Answer 1

Using low level Marshal class methods, it is possible to marshal any type to unmanaged memory. For example, for every double[] array in jaggedArray, allocate unmanaged memory block with Marshal.AllocHGlobal, and copy array members to it using Marshal.Copy Method (Double[], Int32, IntPtr, Int32) method. AllocHGlobal returns IntPtr type, which can be passed to C++ method as poiner, double* in this case.