I am having some trouble marshaling a pointer to an array of strings. It looks harmless like this:
typedef struct
{
char* listOfStrings[100];
} UnmanagedStruct;
This is actually embedded inside another structure like this:
typedef struct
{
UnmanagedStruct umgdStruct;
} Outerstruct;
Unmanaged code calls back into managed code and returns Outerstruct as an IntPtr with memory allocated and values filled in.
Managed world:
[StructLayout(LayoutKind.Sequential)]
public struct UnmanagedStruct
{
[MarshalAs(UnmanagedType.LPArray, ArraySubType=UnmanagedType.LPStr, SizeConst=100)]
public string[] listOfStrings;
}
[StructLayout(LayoutKind.Sequential)]
public struct Outerstruct
{
public UnmanagedStruct ums;
}
public void CallbackFromUnmanagedLayer(IntPtr outerStruct)
{
Outerstruct os = Marshal.PtrToStructure(outerStruct, typeof(Outerstruct));
// The above line FAILS! it throws an exception complaining it cannot marshal listOfStrings field in the inner struct and that its managed representation is incorrect!
}
If I change listOfStrings to simply be an IntPtr then Marshal.PtrToStructure works but now I am unable to rip into listOfStrings and extract the strings one by one.