Convert array<Byte>^ data to const byte* data - C++/CLR

I am trying to call a function in C from C# though c ++

so basically C# -> C++ - >C

In C#, I have byte[] bytes - which reads the information from the file. I am passing the byte array and the size to C++ .

In C++ I get the byte array and the size but I am not able to convert to the specific data types.

void Image::OpenMemFile(array<Byte>^ data, unsigned int size)
{

    Free();
    m_dataStream = data;
    Byte const* streamData = &data[0];   // this is where it throws error 
         // Should I use marshaling here ? What call should that ;be ?
开发者_Go百科         hImage = ::OpenMemImage(streamData ,&nbsp;size);
    modified = false;
}

// this is the function I&nbsp;need to call 
EXIVSIMPLE_API HIMAGE OpenMemImage(const&nbsp;BYTE *data, unsigned int size)
{
   // code
        imgWrap->image = Exiv2::ImageFactory::open(data, size);

}

the C function it needs to call is

Image::AutoPtr ImageFactory::open(const byte* data, long size)
    {
      /// code
    }

I need to help in converting the byte array to const byte* . I realize I need to use Marshaling. Is there a specific function to marshal arrays in C++ ?

Any help is appreciated.

Thanks

pin_ptr<unsigned char> pin_buffer = &data[0];
unsigned char* pData = pin_buffer;