* GCC
** Common Predefined Macros

[[https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html][source]]

#+begin_src C :results verbatim
#include <stdio.h>

int main() {
  // version stuff
  printf("__GNUC__ %d\n", __GNUC__);
  printf("__GNUC_MINOR__ %d\n", __GNUC_MINOR__);
  printf("__GNUC_PATCHLEVEL__ %d\n", __GNUC_PATCHLEVEL__);
  printf("__VERSION__ %s\n", __VERSION__);

  // file related
  printf("__BASE_FILE__ %s\n", __BASE_FILE__);
  printf("__INCLUDE_LEVEL__ %d\n", __INCLUDE_LEVEL__);

  // optimization related
#ifdef __OPTIMIZE__
  printf("__OPTIMIZE__ %d\n", __OPTIMIZE__);
#endif
  printf("__NO_INLINE__ %d\n", __NO_INLINE__);

  switch (__BYTE_ORDER__) {
    case __ORDER_LITTLE_ENDIAN__:
      printf("__BYTE_ORDER__ little\n");
      break;
    case __ORDER_BIG_ENDIAN__:
      printf("__BYTE_ORDER__ big\n");
      break;
    case __ORDER_PDP_ENDIAN__:
      printf("__BYTE_ORDER__ omg\n");
      break;
    default:
      printf("__BYTE_ORDER__ unknown\n");
  }
  printf("__TIMESTAMP__ %s\n", __TIMESTAMP__);
  return 0;
}
#+end_src

#+RESULTS:
: __GNUC__ 4
: __GNUC_MINOR__ 8
: __GNUC_PATCHLEVEL__ 2
: __VERSION__ 4.8.2
: __BASE_FILE__ /tmp/babel-310IHh/C-src-310RYJ.c
: __INCLUDE_LEVEL__ 0
: __NO_INLINE__ 1
: __BYTE_ORDER__ little
: __TIMESTAMP__ Thu Apr 30 14:57:44 2015

** Size Types
#+begin_src C :results verbatim
#include <stdio.h>
#define ESTR(a) STR(a)
#define STR(a) #a

int main() {
  printf("__SIZE_TYPE__ %s (%d)\n", ESTR(__SIZE_TYPE__), sizeof(__SIZE_TYPE__));
  printf("__PTRDIFF_TYPE__ %s (%d)\n", ESTR(__PTRDIFF_TYPE__), sizeof(__PTRDIFF_TYPE__));
  printf("__WCHAR_TYPE__ %s (%d)\n", ESTR(__WCHAR_TYPE__), sizeof(__WCHAR_TYPE__));
  printf("__WINT_TYPE__ %s (%d)\n", ESTR(__WINT_TYPE__), sizeof(__WINT_TYPE__));
  printf("__INTMAX_TYPE__ %s (%d)\n", ESTR(__INTMAX_TYPE__), sizeof(__INTMAX_TYPE__));
  printf("__UINTMAX_TYPE__ %s (%d)\n", ESTR(__UINTMAX_TYPE__), sizeof(__UINTMAX_TYPE__));
  printf("__SIG_ATOMIC_TYPE__ %s (%d)\n", ESTR(__SIG_ATOMIC_TYPE__), sizeof(__SIG_ATOMIC_TYPE__));
  printf("__INT8_TYPE__ %s (%d)\n", ESTR(__INT8_TYPE__), sizeof(__INT8_TYPE__));
  printf("__INT16_TYPE__ %s (%d)\n", ESTR(__INT16_TYPE__), sizeof(__INT16_TYPE__));
  printf("__INT32_TYPE__ %s (%d)\n", ESTR(__INT32_TYPE__), sizeof(__INT32_TYPE__));
  printf("__INT64_TYPE__ %s (%d)\n", ESTR(__INT64_TYPE__), sizeof(__INT64_TYPE__));
  printf("__UINT8_TYPE__ %s (%d)\n", ESTR(__UINT8_TYPE__), sizeof(__UINT8_TYPE__));
  printf("__UINT16_TYPE__ %s (%d)\n", ESTR(__UINT16_TYPE__), sizeof(__UINT16_TYPE__));
  printf("__UINT32_TYPE__ %s (%d)\n", ESTR(__UINT32_TYPE__), sizeof(__UINT32_TYPE__));
  printf("__UINT64_TYPE__ %s (%d)\n", ESTR(__UINT64_TYPE__), sizeof(__UINT64_TYPE__));
  printf("__INT_LEAST8_TYPE__ %s (%d)\n", ESTR(__INT_LEAST8_TYPE__), sizeof(__INT_LEAST8_TYPE__));
  printf("__INT_LEAST16_TYPE__ %s (%d)\n", ESTR(__INT_LEAST16_TYPE__), sizeof(__INT_LEAST16_TYPE__));
  printf("__INT_LEAST32_TYPE__ %s (%d)\n", ESTR(__INT_LEAST32_TYPE__), sizeof(__INT_LEAST32_TYPE__));
  printf("__INT_LEAST64_TYPE__ %s (%d)\n", ESTR(__INT_LEAST64_TYPE__), sizeof(__INT_LEAST64_TYPE__));
  printf("__UINT_LEAST8_TYPE__ %s (%d)\n", ESTR(__UINT_LEAST8_TYPE__), sizeof(__UINT_LEAST8_TYPE__));
  printf("__UINT_LEAST16_TYPE__ %s (%d)\n", ESTR(__UINT_LEAST16_TYPE__), sizeof(__UINT_LEAST16_TYPE__));
  printf("__UINT_LEAST32_TYPE__ %s (%d)\n", ESTR(__UINT_LEAST32_TYPE__), sizeof(__UINT_LEAST32_TYPE__));
  printf("__UINT_LEAST64_TYPE__ %s (%d)\n", ESTR(__UINT_LEAST64_TYPE__), sizeof(__UINT_LEAST64_TYPE__));
  printf("__INT_FAST8_TYPE__ %s (%d)\n", ESTR(__INT_FAST8_TYPE__), sizeof(__INT_FAST8_TYPE__));
  printf("__INT_FAST16_TYPE__ %s (%d)\n", ESTR(__INT_FAST16_TYPE__), sizeof(__INT_FAST16_TYPE__));
  printf("__INT_FAST32_TYPE__ %s (%d)\n", ESTR(__INT_FAST32_TYPE__), sizeof(__INT_FAST32_TYPE__));
  printf("__INT_FAST64_TYPE__ %s (%d)\n", ESTR(__INT_FAST64_TYPE__), sizeof(__INT_FAST64_TYPE__));
  printf("__UINT_FAST8_TYPE__ %s (%d)\n", ESTR(__UINT_FAST8_TYPE__), sizeof(__UINT_FAST8_TYPE__));
  printf("__UINT_FAST16_TYPE__ %s (%d)\n", ESTR(__UINT_FAST16_TYPE__), sizeof(__UINT_FAST16_TYPE__));
  printf("__UINT_FAST32_TYPE__ %s (%d)\n", ESTR(__UINT_FAST32_TYPE__), sizeof(__UINT_FAST32_TYPE__));
  printf("__UINT_FAST64_TYPE__ %s (%d)\n", ESTR(__UINT_FAST64_TYPE__), sizeof(__UINT_FAST64_TYPE__));
  printf("__INTPTR_TYPE__ %s (%d)\n", ESTR(__INTPTR_TYPE__), sizeof(__INTPTR_TYPE__));
  printf("__UINTPTR_TYPE__ %s (%d)\n", ESTR(__UINTPTR_TYPE__), sizeof(__UINTPTR_TYPE__));
  return 0;
}
#+end_src

#+RESULTS:
#+begin_example
__SIZE_TYPE__ long unsigned int (8)
__PTRDIFF_TYPE__ long int (8)
__WCHAR_TYPE__ int (4)
__WINT_TYPE__ unsigned int (4)
__INTMAX_TYPE__ long int (8)
__UINTMAX_TYPE__ long unsigned int (8)
__SIG_ATOMIC_TYPE__ int (4)
__INT8_TYPE__ signed char (1)
__INT16_TYPE__ short int (2)
__INT32_TYPE__ int (4)
__INT64_TYPE__ long int (8)
__UINT8_TYPE__ unsigned char (1)
__UINT16_TYPE__ short unsigned int (2)
__UINT32_TYPE__ unsigned int (4)
__UINT64_TYPE__ long unsigned int (8)
__INT_LEAST8_TYPE__ signed char (1)
__INT_LEAST16_TYPE__ short int (2)
__INT_LEAST32_TYPE__ int (4)
__INT_LEAST64_TYPE__ long int (8)
__UINT_LEAST8_TYPE__ unsigned char (1)
__UINT_LEAST16_TYPE__ short unsigned int (2)
__UINT_LEAST32_TYPE__ unsigned int (4)
__UINT_LEAST64_TYPE__ long unsigned int (8)
__INT_FAST8_TYPE__ signed char (1)
__INT_FAST16_TYPE__ long int (8)
__INT_FAST32_TYPE__ long int (8)
__INT_FAST64_TYPE__ long int (8)
__UINT_FAST8_TYPE__ unsigned char (1)
__UINT_FAST16_TYPE__ long unsigned int (8)
__UINT_FAST32_TYPE__ long unsigned int (8)
__UINT_FAST64_TYPE__ long unsigned int (8)
__INTPTR_TYPE__ long int (8)
__UINTPTR_TYPE__ long unsigned int (8)
#+end_example