今天用MinGW(http://www.mingw.org/)編譯一個專案，怎麼也想不起來用哪一個巨集來判斷用的是mingw的gcc編譯器，不得以只好在標頭檔案中搜索，找了半天終於發現是：__MINGW32__。

後來我就想，有沒有一個辦法能把編譯器的所有預定義巨集列出來呢？於是左google右google，終於讓我用“mingw predefined macro”這幾個關鍵字打出瞭解決方案：

• 先定義一個最簡單的C檔案（其實任何C檔案都可以），只有一行： 

      int main(void) {}

• 在命令列執行如下命令：

      gcc -dM -E test.c
      編譯器會列出所有的預定義巨集，如下：
#define __DBL_MIN_EXP__ (-1021)
#define __FLT_MIN__ 1.17549435e-38F
#define _WIN32 1
#define __CHAR_BIT__ 8
#define __WCHAR_MAX__ 65535U
#define __DBL_DENORM_MIN__ 4.9406564584124654e-324
#define __FLT__METHOD__ 2
#define __DBL_MIN_10_EXP__ (-307)
#define __FINITE_MATH_ONLY__ 0
#define __GNUC_PATCHLEVEL__ 0
#define _stdcall __attribute__((__stdcall__))
#define __DEC64_MAX_EXP__ 385
#define __SHRT_MAX__ 32767
#define __LDBL_MAX__ 1.18973149535723176502e+4932L
#define __GXX_TYPEINFO_EQUALITY_INLINE 0
#define __UINTMAX_TYPE__ long long unsigned int
#define __DEC32_EPSILON__ 1E-6DF
#define __LDBL_MAX_EXP__ 16384
#define __SCHAR_MAX__ 127
#define __DBL_DIG__ 15
#define __SIZEOF_INT__ 4
#define __SIZEOF_POINTER__ 4
#define __USER_LABEL_PREFIX__ _
#define __STDC_HOSTED__ 1
#define __WIN32 1
#define __LDBL_HAS_INFINITY__ 1
#define __FLT_EPSILON__ 1.19209290e-7F
#define __LDBL_MIN__ 3.36210314311209350626e-4932L
#define __DEC32_MAX__ 9.999999E96DF
#define __MINGW32__ 1
。。。

當然，你也可以換成你想檢視的編譯器，如android的編譯器：

  arm-eabi-gcc -dM -E test.c
則Android的Toolchain編譯器的所有預定義巨集顯示如下：
#define __DBL_MIN_EXP__ (-1021)
#define __FLT_MIN__ 1.17549435e-38F
#define __DEC64_DEN__ 0.000000000000001E-383DD
#define __CHAR_BIT__ 8
#define __WCHAR_MAX__ 4294967295U
#define __DBL_DENORM_MIN__ 4.9406564584124654e-324
#define __FLT__METHOD__ 0
#define __DBL_MIN_10_EXP__ (-307)
#define __FINITE_MATH_ONLY__ 0
#define __ARMEL__ 1
#define __GNUC_PATCHLEVEL__ 1
#define __DEC64_MAX_EXP__ 384
#define __SHRT_MAX__ 32767
#define __LDBL_MAX__ 1.7976931348623157e+308L
#define __UINTMAX_TYPE__ long long unsigned int
#define __DEC32_EPSILON__ 1E-6DF
#define __CHAR_UNSIGNED__ 1
#define __LDBL_MAX_EXP__ 1024
#define __SCHAR_MAX__ 127
#define __DBL_DIG__ 15
#define __USER_LABEL_PREFIX__
#define __STDC_HOSTED__ 1
#define __LDBL_HAS_INFINITY__ 1
#define __FLT_EPSILON__ 1.19209290e-7F
#define __APCS_32__ 1
#define __LDBL_MIN__ 2.2250738585072014e-308L
#define __DEC32_MAX__ 9.999999E96DF
#define __DECIMAL_DIG__ 17
#define __LDBL_HAS_QUIET_NAN__ 1
#define __GNUC__ 4
#define __FLT_HAS_DENORM__ 1
#define __DBL_MAX__ 1.7976931348623157e+308
#define __DBL_HAS_INFINITY__ 1
#define __DEC32_MIN_EXP__ (-95)
#define __THUMB_INTERWORK__ 1
#define __LDBL_HAS_DENORM__ 1
#define __DEC128_MAX__ 9.999999999999999999999999999999999E6144DL
#define __DEC32_MIN__ 1E-95DF
#define __DBL_MAX_EXP__ 1024
#define __DEC128_EPSILON__ 1E-33DL
#define __LONG_LONG_MAX__ 9223372036854775807LL
#define __GXX_ABI_VERSION 1002
#define __SOFTFP__ 1
#define __FLT_MIN_EXP__ (-125)
#define __DBL_MIN__ 2.2250738585072014e-308
#define __USES_INITFINI__ 1
#define __DEC128_MIN__ 1E-6143DL
#define __REGISTER_PREFIX__
#define __DBL_HAS_DENORM__ 1
#define __NO_INLINE__ 1
#define __FLT_MANT_DIG__ 24
#define __VERSION__ "4.2.1"
#define __DEC64_EPSILON__ 1E-15DD
#define __DEC128_MIN_EXP__ (-6143)
#define __SIZE_TYPE__ unsigned int
#define __DEC32_DEN__ 0.000001E-95DF
#define __ELF__ 1
#define __FLT_RADIX__ 2
#define __LDBL_EPSILON__ 2.2204460492503131e-16L
#define __VFP_FP__ 1
#define __FLT_HAS_QUIET_NAN__ 1
#define __FLT_MAX_10_EXP__ 38
#define __LONG_MAX__ 2147483647L
#define __FLT_HAS_INFINITY__ 1
#define __DEC64_MAX__ 9.999999999999999E384DD
#define __DEC64_MANT_DIG__ 16
#define __DEC32_MAX_EXP__ 96
#define __DEC128_DEN__ 0.000000000000000000000000000000001E-6143DL
#define __GXX_MERGED_TYPEINFO_NAMES 0
#define __LDBL_MANT_DIG__ 53
#define __DBL_HAS_QUIET_NAN__ 1
#define __WCHAR_TYPE__ unsigned int
#define __DEC64_MIN_EXP__ (-383)
#define __FLT_DIG__ 6
#define __INT_MAX__ 2147483647
#define __FLT_MAX_EXP__ 128
#define __DBL_MANT_DIG__ 53
#define __DEC64_MIN__ 1E-383DD
#define __WINT_TYPE__ unsigned int
#define __LDBL_MIN_EXP__ (-1021)
#define __arm__ 1
#define __LDBL_MAX_10_EXP__ 308
#define __DBL_EPSILON__ 2.2204460492503131e-16
#define __DEC__METHOD__ 2
#define __INTMAX_MAX__ 9223372036854775807LL
#define __FLT_DENORM_MIN__ 1.40129846e-45F
#define __FLT_MAX__ 3.40282347e+38F
#define __FLT_MIN_10_EXP__ (-37)
#define __INTMAX_TYPE__ long long int
#define __DEC128_MAX_EXP__ 6144
#define __GNUC_MINOR__ 2
#define __DEC32_MANT_DIG__ 7
#define __DBL_MAX_10_EXP__ 308
#define __LDBL_DENORM_MIN__ 4.9406564584124654e-324L
#define __STDC__ 1
#define __ARM_ARCH_4T__ 1
#define __PTRDIFF_TYPE__ int
#define __ARM_EABI__ 1
#define __DEC128_MANT_DIG__ 34
#define __LDBL_MIN_10_EXP__ (-307)
#define __LDBL_DIG__ 15
#define __GNUC_GNU_INLINE__ 1