Gnu C++ macro __cplusplus standard conform?

The Gnu C++ compiler seems to define `__cplusplus` to be `1` ``` #include <iostream> int main() { std::cout << __cplusplus << std::endl; } ``` This prints `1` with gcc in standard c++ mode, as well as in C++0x mode, with gcc 4.3.4, and gcc 4.7.0. The C++11 FDIS says in "16.8 Predefined macro names [cpp.predefined]" that The name `__cplusplus` is defined to the value 201103L when compiling a C++ translation unit. (Footnote: It is intended that future versions of this standard will replace the value of this macro with a greater value. Non-conforming com- pilers should use a value with at most five decimal digits.) The old std C++03 had a similar rule. Is the GCC deliberatly setting this to `1`, because it is "non-conforming"? By reading through that list I thought that I could use `__cplusplus` to check in a portable way if I have a C++11 enabled compiler. But with g++ this does not seem to work. I know about the `...EXPERIMENTAL...` macro, but got curious why g++ is defining `__cplusplus` this way. My original problem was switch between different null-pointer-variants. Something like this: ``` #if __cplusplus > 201100L # define MYNULL nullptr #else # define MYNULL NULL #endif ``` Is there a simple and reasonably portable way to implement such a switch?