I looked up at my g++ compiler and i found this: http://pastebin.com/VpSsEkBY

That g++ compiler is using a gnu extension through the __GNUG__ code path. The "true" C++ code path is at line 11.

Edit:

Answering the person below,the file that defines NULL is "stddef.h"

An example of the file online that defines NULL is here: https://github.com/Alexpux/mingw-w64/blob/d0d7f784833bbb0b2d...