If i remember correctly
void foo();
in C++ is equivalent to
void foo(void)
in C. And the type of 'x' (character literal) in C++ is char. Apart
from that C++ is a superset of C.
But i think it hardly helps him. In the end he will have to follow the
conventions the others use. So I'd recommend reading the code you will
work on. We use C++ too. And sadly it is hardly consistent since it is
written by loads of people and noone bothers to check. But it's mostly
readable. No template metaprogramming voodoo. Thankfully i work on some
internal tools right now so i can get away with C and yacc. I'm even
using plan9 right now to write documentation for one of them :)