What is the point of the C99 standard?

Question

C99 adds several useful features to the language, yet I find it difficult to recommend any practice which depends upon C99. The reason for this is because there are few (any?) actual implementations of the C99 language. Sure, there is limited support in a few compilers, but nobody wants spend the time to write C code only to have it be unportable.

This is frustrating given that the standard was written and finalized over 10 years ago now. Plus I hear discussions of a C1x from time to time, and I wonder why someone would be taking steps to revise the language given that the current version of the language isn't yet implemented.

So my question is, as joe blow C programmer today, what is useful w.r.t. the C99 standard to me (if any)?

Answer 1

C99 brings features that really makes programming in C easier and more error safe:

• designated initializers
• compound literals
• for-scope variables
• fixed width integer types

The language is also much more expressive with

• variadic macros
• inline functions

On my linux machine I have four compilers that support C99 to a satisfying extent that make this usable on a daily base: gcc, clang, opencc and icc.

The first two are open source compilers where clang trying to be code compatible to gcc (meaning C99 support is about the same).

The later two are from the two major CPU producers and are commercial but with generous license policy for non commercial users. Their C99 is a bit less, in particular their support for inline seems not completely consistent with the standard, yet.

Answer 2

MSVC does not, nor will it probably ever, support C99. But Microsoft has little incentive to update their C compiler. It's not like they will lose much business over it.

But there are plenty of compilers that have support for C99.

http://en.wikipedia.org/wiki/C99#Implementations

Regarding gcc:

http://gcc.gnu.org/c99status.html

You are right that perhaps C99 is not useful for library code (and may never be without Microsoft's support), but if you're working on an in-house or personal project where you can pick the compilers and tools, then the portability is not much of an issue.