extern C and static data type problem with g++

[Luu Vo]

In RH Linux 9, when compiling my C++ program with lines as below:

extern "C" struct {int x};
static enum E{A=0, B, C};

g++ said:

storage class specified for field `x'
`static' can only be specified for objects and functions

Is this just the implementation of g++? That means I can't use static and
extern "C" for those lines of code?

Another question: with GNU g++/gcc compiler and its C++ library, can I use
both traditional C++ lib (e.g., classic iostream) and standard C++ lib
(e.g., standard iostream) in my C++ program. Are the both libraries
implemented in glibstdc++?

Any help will be appreciated.

Luu Vo.