List up #define list in C code of my system

자신의 시스템에서 어떤 system #define이 걸려있는지 알고 싶을 때가 있다.

크로스 플랫폼 지원 애플리케이션 설계 시 이러한 macro 변수 활용이 필요하다.

There are times when you want to know which system #defines are running on your system.

When designing cross-platform support applications, it is necessary to utilize these macro variables.

$ touch foo.h; cpp -dM foo.h
#define __SSP_STRONG__ 3                                                                                                                                                                                                                                                          
#define __DBL_MIN_EXP__ (-1021)                                                                                                                                                                                                                                                   
#define __UINT_LEAST16_MAX__ 0xffff                                                                                                                                                                                                                                               
#define __ATOMIC_ACQUIRE 2                                                                                                                                                                                                                                                        
#define __FLT128_MAX_10_EXP__ 4932                                                                                                                                                                                                                                                
#define __FLT_MIN__ 1.17549435082228750796873653722224568e-38F                                                                                                                                                                                                                    
#define __GCC_IEC_559_COMPLEX 2                                                                                                                                                                                                                                                   
#define __UINT_LEAST8_TYPE__ unsigned char  
...

in case of x86

$ touch foo.h; x86_64-linux-gnu-cpp-11 -dM foo.h 
...
#define __x86_64__ 1
...

in case of aarch64

$  touch foo.h; /opt/toolchains/gcc-linaro-6.5.0-2018.12-x86_64_aarch64-linux-gnu/bin/aarch64-linux-gnu-cpp -dM foo.h
...
#define __aarch64__ 1  
...