Sorry; I didn't realise that _Generic is a C11 keyword: http://en.wikipedia.org/wiki/C11_(C_standard_revision) http://en.wikipedia.org/wiki/C11_(C_standard_rev

Sorry; I didn't realise that _Generic is a C11 keyword: http://en.wikipedia.org/wiki/C11_(C_standard_revision) http://en.wikipedia.org/wiki/C11_(C_standard_revision) Also, that SO post is about C++, not C. No, it's about both C++ and C: Because C++ is based on the C standard (1.1/2, C++03) and C99 is a normative reference (1.2/1, C++03) these also apply, from the 1999 C Standard... See section 7.1.3 of the relevant standard: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1124.pdf Also, the divergence has actually been lessened since the C++11 committee worked closely with the C11 committee to bring the standards closer together. That's part of why Microsoft is picking up a lot of C99 as part of their work for implementing C++11.