Is there a #define for C99?

c macros c99
klynch picture klynch · Jan 22, 2010 · Viewed 7.5k times · Source

I want to do something in C99 one way, otherwise to perform it another way. What is the #define to check for?

#ifdef C99
...
#else
...
#endif

Answer

Khelben picture Khelben · Jan 22, 2010

There is not an specific #define value. Just check __STDC_VERSION__ and define it yourself! ;-)

#if __STDC_VERSION__ >= 199901L
/* C99 code */
#define C99
#else
/* Not C99 code */
#endif


#ifdef C99
/*My code in C99 format*/
#else
/*My code in C99 format*/
#endif

EDIT: A more general snippet, from here. I've just changed the defined names, just in case you'll use them a lot on the code:

#if defined(__STDC__)
# define C89
# if defined(__STDC_VERSION__)
#  define C90
#  if (__STDC_VERSION__ >= 199409L)
#   define C94
#  endif
#  if (__STDC_VERSION__ >= 199901L)
#   define C99
#  endif
#  if (__STDC_VERSION__ >= 201112L)
#   define C11
#  endif
# endif
#endif

Related questions

The most useful user-made C-macros (in GCC, also C99)?

What C macro is in your opinion is the most useful? I have found the following one, which I use to do vector arithmetic in C: #define v3_op_v3(x, op, y, z) {z[0]=x[0] op y[0]; \ z[1]=x[1] …

Read More
Cleaning up C/C++ code reveals problems with variadic macros

We're doing some code cleanup, fixing signed/unsigned comparisons, running static analysis, etc, on the code base of C, C++, and Java. One of the warnings we're getting is warning: ISO C does not permit named variadic macros And its …

Read More
What is ":-!!" in C code?

I bumped into this strange macro code in /usr/include/linux/kernel.h: /* Force a compilation error if condition is true, but also produce a result (of value 0 and type size_t), so the expression can be used e.g. …

Read More