You say you don't like xxd because it leaves the file unreadable. Fair enough. It would be simple to write your own utility that encodes the data in a different format, since you specifically want strings as input and output. You can take advantage of string literal concatenation to make this easily readable.
const char* str =
#include "foo.h"
;
foo.h:
" int x;" "\n"
" void main(){}" "\n"
I briefly tried using C++11's raw string literals, which would have allowed using the file without any reformatting, but it did not work. The #include is considered to be part of the string rather than including the file as desired.
