Inter Process Data Exchange

Hello,
I want my MFC C++ appl. to exchance data (large array content) with a pure C written app.
I need a 'process to process' approach regarding argument data exchange because of memory conflicts that happen elsewise, e.g. if I convert my C app into a DLL and use loadLibrary, etc. etc.
I figure I need using memory files, to exchange data between processes.
I have written a small C app that should read memory files being passed on by my C++ app,
but I can not figure out how to create a memory file in my MFC C++ app that can be identified by the C written app and read by it .
I need some source code example explaining and showing how to.
So how do I create a memory file from an MFC C++ appl. that is accessible from a C application?
I already know that MFC contains a battery of MemFile functions, but these are not available in just C..., this is the problem i think I am facing - I believe there must be a solution to this.
Thank you in advance for any replies....
Best regards
Gustav