What are the gcc predefined macros for the compiler's version number?

From the gnu cpp manual...

---

__GNUC__
__GNUC_MINOR__
__GNUC_PATCHLEVEL__

These macros are defined by all GNU compilers that use the C preprocessor: C, C++, Objective-C and Fortran. Their values are the major version, minor version, and patch level of the compiler, as integer constants. For example, GCC 3.2.1 will define __GNUC__ to 3, __GNUC_MINOR__ to 2, and __GNUC_PATCHLEVEL__ to 1. These macros are also defined if you invoke the preprocessor directly.

__GNUC_PATCHLEVEL__ is new to GCC 3.0; it is also present in the widely-used development snapshots leading up to 3.0 (which identify themselves as GCC 2.96 or 2.97, depending on which snapshot you have).

If all you need to know is whether or not your program is being compiled by GCC, or a non-GCC compiler that claims to accept the GNU C dialects, you can simply test __GNUC__. If you need to write code which depends on a specific version, you must be more careful. Each time the minor version is increased, the patch level is reset to zero; each time the major version is increased (which happens rarely), the minor version and patch level are reset. If you wish to use the predefined macros directly in the conditional, you will need to write it like this:

          /* Test for GCC > 3.2.0 */
          #if __GNUC__ > 3 || \
              (__GNUC__ == 3 && (__GNUC_MINOR__ > 2 || \
                                 (__GNUC_MINOR__ == 2 && \
                                  __GNUC_PATCHLEVEL__ > 0)))

__GNUC__, __GNUC_MINOR__ and __GNUC_PATCHLEVEL__.

For instance, GCC 4.0.1 will do:

#define __GNUC__ 4
#define __GNUC_MINOR__ 0
#define __GNUC_PATCHLEVEL__ 1

Here is a little command line that is nice to remember when you are wondering which are the predefined preprocessor directives defined by the GNU GCC compiler under your current programming environment:

gcc -E -dM - < /dev/null |less

There's 3 macros for the gcc version you can test on.

__GNUC_MINOR__ 
 __GNUC_PATCHLEVEL__ 
 __GNUC__ 

e.g. my gcc v 4.3.1 defines them as such:

#define __GNUC_MINOR__ 1
#define __GNUC_PATCHLEVEL__ 3
#define __GNUC__ 4

You can see the "buitin" macros defined by running

gcc -E -dM -x c /dev/null