Just how portable is C++?

C++ is perhaps the most popular language for AI programming.  I find, however, that my Asa programs in C++ will compile and run with some C++ compilers but not with others. (At least not without some workarounds.) I understand that some of the libraries have been changed in the last couple years. Just how portable is C++?  (The code in my 14 May 2012 blog will run with the Dev-C++ compiler but not MS C++.)