notes.txt

__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



查看 GCC 内建的宏定义

GCC 有很多内建的宏，这些宏的名字很难记，但是如果看到宏的名字又很容易理解这个宏的意义。

up in the air