Marshalling a struct containing char**

[mads.toustrup]

Hi,

I have an application in which I need to call an unmanaged library.
The method I need to call take the following struct as a paramter:

struct someStruct
{
char **names;
int len;
};

The struct is sent to the .dll, and is supposed to return with 'names'
filled up.

Since 'names' is an array I've tried the following:

[StructLayout(LayoutKind.Sequential)]
public struct someStruct
{
[MarshalAs(UnmanagedType.LPArray)]
public string[] names;

public int len;
};

and

[StructLayout(LayoutKind.Sequential)]
public struct listmots
{
public IntPtr guid;

public int len;
};

I've tried sending the struct with with an out parameter and with the
ref parameter when making the interop, but no luck. Should I send a
IntPtr instead?

I usually get an AccessViolationException, "Attempted to read or write
protected memory. This is often an indication that other memory is
corrupt."