If not, what features of C99 are still missing?
https://docs.microsoft. com/en-us/cpp/visual-cpp-language-conformance
The compiler’s support for C99 Preprocessor rules is incomplete in Visual Studio 2017. Variadic macros are supported , but there are many bugs in the preprocessor’s behavior.
https://docs.microsoft.com/en-us/cpp/build/walkthrough-compile-ac-program-on- the-command-line
The Visual C++ C compiler is generally compatible with the ISO C99 standard, but not strictly compliant. In most cases, portable C code will compile and run as expected. Visual C++ does not support most of the changes in ISO C11. Certain library functions and POSIX function names are deprecated by the Visual C++ compiler. The functions are supported, but the preferred names have changed. For more information, see Security Features in the CRT and Compil er Warning (level 3) C4996.
Please remember that Visual C is ultimately a C implementation, not a real C environment. Compatibility is a good example of the common heritage of C and C Although the syntax is similar, the two are very different languages.
The latest version of Visual Studio has seen improved support for C99. The latest version of VS2017 is now Are all C99s supported?
If not, what features of C99 are still missing?
No.
https://docs.microsoft.com/en-us/cpp/visual-cpp- language-conformance
The compiler’s support for C99 Preprocessor rules is incomplete in Visual Studio 2017. Variadic macros are supported, but there are many bugs in the preprocessor’s behavior.< /p>
https://docs.microsoft.com/en-us/cpp/build/walkthrough-compile-ac-program-on-the-command-line
The Visual C++ C compiler is generally compatible with the ISO C99 standard, but not strictly compliant. In most cases, portable C code will compile and run as expected. Visual C++ does not support most of the changes in ISO C11. Certain library functions and POSIX function names are deprecated by the Visual C++ compiler. The functions are supported, but the preferred names have changed. For more information , see Security Features in the CRT and Compiler Warning (level 3) C4996.
Remember, Visual C is ultimately a C implementation, not a real C environment. Compatibility is a nice side effect of the common heritage of C and C, but despite the similar syntax, the two are very different languages.