Hacking SD File access (borrowing FS code from loadiine_gx2)

[Ape8000]

[EDIT] My bad. Think I'm trying to include c++ in a c file. Let me try again using C stdio.h functions. [EDIT]

[EDIT 2]
Fixed. I needed to use standard fopen, fread, etc and add:
#include <unistd.h>
#include <fcntl.h>
See post here for results.
[EDIT 2]

I'm trying to add a feature to ddd so that it saves the selected IP to SD.
I borrowed the FS directory from loadiine_gx2.
Also utils\StringTools.cpp & .h

When I compile I get this error when adding #include "fs/CFile.hpp":

In file included from c:/Projects/ddd/src/discdumper.c:16:0:
c:/Projects/ddd/src/fs/CFile.hpp:5:18: fatal error: string: No such file or directory
#include <string>

I do not see any difference between the ddd and loadiine_gx2 makefiles that would cause this.

What am I missing? (Probably a library, but which one?)
Is there an easier way to read write to the sd card?

I may also end up having a problem with #include <vector>

FWIW, I have added the mount/unmounts to the main routine and added file read/write to Get/SetServerIp.
If I can get std::string to work, it should be done.

Thanks.

PS. Is there a good place to learn Wii U homebrew coding?