Is the C part of the C++ library automatically C99?

Question

Are all the functions in a conformant C++98/03/0x implementation completely C99 conformant?

I thought C++0x added some C99 (language) features, but never heard or read anything definitive about the C library functions.

Just to avoid any confusion, I'm talking about a C++ program using functions declared in the <c*> header set.

Thanks.

Answer 1

Most of the C99 standard library has been imported in C++0X but not all. From memory, in what wasn't imported there are

• <ctgmath> simply includes <ccomplex> and <cmath>,
• <ccomplex> behaves as if it included <complex>
• <cmath> has quite a few adjustment (providing overload and template functions completing the C99 provided one)
• Some other headers (<cstdbool>, <iso646.h>, ...) have adjustments to take differences between language into account (bool is primitive in C++, a macro provided by <stdbool.h> in C for instance), but nothing of the scope of the math part.

The headers <xxx.h> whose <cxx> form doesn't behaves as the C99 version simply declares the content of <cxxx> in the global namespace, they aren't nearer of the C99 <xxx.h> content.

A related thing: C++0X provides some headers in both cxxx and xxx.h forms which aren't defined in C99 (<cstdalign> and <cuchar>, the second one is defined in a C TR)

(I remembered that a bunch of mathematical functions from C99 had been put in TR1 but not kept in C++0X, I was mistaken, that bunch of mathematical functions weren't part of C99 in the first place).

Answer 2

No. C++03 is aligned with ANSI C89/ISO C90, not C99.

The upcoming C++0x standard is expected to be aligned to some degree with C99. See paragraph 17.6.1.2 in the current draft which lists ccomplex, cinttypes, cstdint etc. Note that, as AProgrammer mentions, some headers aren't exactly the same; further, that the header cuchar is aligned with the C Technical Report 19769 rather than C99.