Question

I have a embeded record in delphi like this:

TKernel = packed record
    State: Integer;
end;
TKernels = array[0..19] of TKernel;

TShell = packed record
  Kernels: TKernels;
end;

In this,

SizeOf(TShell) = 20 * SizeOf(TKernel).

But If I use C#：

struct Shell
{
    Kernel[] Kernels;
    public Shell(int i = 20)
    {
        Kernels = new Kernel[20];
    }
}

then:
Marshal.SizeOf(Shell) == 4

that means Kernels is just a pointer.
I want to InterOp C# with Delphi, so I need there memory structure is the same, So how should I declare the struct in C# besides write 20 likes of Kernel KernelOne; Kernel KernelTwo。。。

Answer 1

I would always avoid unsafe if at all possible since unsafe code is, well, not safe. And it is quite possible to avoid in this case:

[StructLayout(LayoutKind.Sequential, Pack=1)]
struct Kernel
{
    int State;
}

[StructLayout(LayoutKind.Sequential, Pack=1)]
struct Shell
{
    [MarshalAs(UnmanagedType.ByValArray, SizeConst=20)]
    Kernel[] Kernels;
}