g++ Preprocessor Output
Create Preprocessor Output
Run the following command, and you can see the output from the preprocessor of g++
- All
#include,#define,#if,#ifdefare removed and replaced with the actual value - Any line starts with # tells
- line number : the first field
- file name : the 2nd field
- flag : the 3rd / 4th field(s), See the link for details about the flag: https://gcc.gnu.org/onlinedocs/cpp/Preprocessor-Output.html
- 1 - start of a new file
- 2 - return to a file (after #include)
- 3 - following from a system header file
- 4 - following having an implicit
extern "C"
g++ -E test.cpp
#include <stdio.h>
int main() {
const size_t as = 10;
return as;
}
Check pre-defined macros in
cpp -dM foo.h
Or
g++ -E -dM foo.h
- Note:
foo.his a empty dummy file
Output
#define OBJC_NEW_PROPERTIES 1
#define _LP64 1
#define __APPLE_CC__ 6000
#define __APPLE__ 1
...
#define __BLOCKS__ 1
#define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__
#define __CHAR16_TYPE__ unsigned short
#define __CHAR32_TYPE__ unsigned int
#define __CHAR_BIT__ 8
...
#define __INT16_MAX__ 32767
#define __INT16_TYPE__ short
...
#define __INT32_MAX__ 2147483647
#define __INT32_TYPE__ int
...
#define __INT64_MAX__ 9223372036854775807LL
#define __INT64_TYPE__ long long int
...
#define __INT8_MAX__ 127
#define __INT8_TYPE__ signed char
...
#define __INTMAX_MAX__ 9223372036854775807L
#define __INTMAX_TYPE__ long int
...
#define __INTPTR_MAX__ 9223372036854775807L
#define __INTPTR_TYPE__ long int
...
#define __SIZEOF_DOUBLE__ 8
#define __SIZEOF_FLOAT__ 4
#define __SIZEOF_INT128__ 16
#define __SIZEOF_INT__ 4
#define __SIZEOF_LONG_DOUBLE__ 16
#define __SIZEOF_LONG_LONG__ 8
#define __SIZEOF_LONG__ 8
#define __SIZEOF_POINTER__ 8
#define __SIZEOF_PTRDIFF_T__ 8
#define __SIZEOF_SHORT__ 2
#define __SIZEOF_SIZE_T__ 8
#define __SIZEOF_WCHAR_T__ 4
#define __SIZEOF_WINT_T__ 4
#define __SIZE_FMTX__ "lX"
#define __SIZE_FMTo__ "lo"
#define __SIZE_FMTu__ "lu"
#define __SIZE_FMTx__ "lx"
#define __SIZE_MAX__ 18446744073709551615UL
#define __SIZE_TYPE__ long unsigned int
#define __SIZE_WIDTH__ 64
...
#define __USER_LABEL_PREFIX__ _
#define __VERSION__ "4.2.1 Compatible Apple LLVM 10.0.0 (clang-1000.10.44.2)"
#define __WCHAR_MAX__ 2147483647
#define __WCHAR_TYPE__ int
#define __WCHAR_WIDTH__ 32
#define __WINT_MAX__ 2147483647
#define __WINT_TYPE__ int
#define __WINT_WIDTH__ 32
...
#define __cplusplus 199711L
#define __cpp_exceptions 199711
#define __cpp_rtti 199711
#define __cpp_threadsafe_static_init 200806
#define __llvm__ 1
#define __nonnull _Nonnull
#define __null_unspecified _Null_unspecified
#define __nullable _Nullable
#define __pic__ 2
#define __private_extern__ extern
#define __strong
#define __tune_core2__ 1
#define __unsafe_unretained
#define __weak __attribute__((objc_gc(weak)))
#define __x86_64 1
#define __x86_64__ 1
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