Interop c++ struct in c# variable string size

i transfer over ipc a struct from unmanaged into managed code. Is it possible to transfer a string without set a constant size or fill the rest auf the bytes into the last member of the struct ?

c++ struct

typedef union
{
    struct
    { 
         int id;
         string Data;
    };
    开发者_StackOverflowchar bytes[];
} SocketData;

c# struct

   [StructLayoutAttribute(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
    public struct SocketData
    {
        public int id;
        public string Data;
    }

Convert bytes to struct

public static object RawDeserialize(byte[] rawData, int position, Type anyType)
{
    var rawsize = rawData.Length;
    //if (rawsize > rawData.Length)
    //    return null;
    var buffer = Marshal.AllocHGlobal(rawsize);
    Marshal.Copy(rawData, position, buffer, rawsize);
    var retobj = Marshal.PtrToStructure(buffer, anyType);
    Marshal.FreeHGlobal(buffer);
    return retobj;
}

Do not do that, std::string is not POD. Even with different compiler/linker versions std::string is NOT binary compatible*, you cannot expect it to be compatible between managed and unmanaged world.

* By this I mean, If you have a DLL build using XX compiler version (even of same vendor), and passing std::string from a client (EXE), which is built using older/newer compiler/header version - the string object may not be same.

This other post might help you.

It involves using StringBuilder instead.

I wonder why you need variable buffer lengths since Sockets usually use fixed length buffers