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).