This is an alphabetical list of the C preprocessor symbols that the Autoconf macros define. To work with Autoconf, C source code needs to use these names in #if directives.
#if
__CHAR_UNSIGNED__
__EXTENSIONS__
__PROTOTYPES
_ALL_SOURCE
_FILE_OFFSET_BITS
_GNU_SOURCE
_LARGE_FILES
_LARGEFILE_SOURCE
_MINIX
_POSIX_1_SOURCE
_POSIX_PTHREAD_SEMANTICS
_POSIX_SOURCE
_POSIX_VERSION
C_ALLOCA
C_GETLOADAVG
CLOSEDIR_VOID
const
CXX_NO_MINUS_C_MINUS_O
DGUX
DIRENT
F77_DUMMY_MAIN
F77_FUNC
F77_FUNC_
F77_MAIN
F77_NO_MINUS_C_MINUS_O
FC_FUNC
FC_FUNC_
FC_MAIN
FC_NO_MINUS_C_MINUS_O
GETGROUPS_T
GETLODAVG_PRIVILEGED
GETPGRP_VOID
gid_t
GWINSZ_IN_SYS_IOCTL
HAVE__BOOL
HAVE_ALLOCA_H
HAVE_CONFIG_H
HAVE_DECL_STRERROR_R
HAVE_DECL_
HAVE_DIRENT_H
HAVE_DOPRNT
HAVE_
HAVE_GETMNTENT
HAVE_INT16_T
HAVE_INT32_T
HAVE_INT64_T
HAVE_INT8_T
HAVE_INTMAX_T
HAVE_INTPTR_T
HAVE_LONG_DOUBLE
HAVE_LONG_DOUBLE_WIDER
HAVE_LONG_FILE_NAMES
HAVE_LONG_LONG_INT
HAVE_LSTAT_EMPTY_STRING_BUG
HAVE_MALLOC
HAVE_MBRTOWC
HAVE_MMAP
HAVE_NDIR_H
HAVE_NLIST_H
HAVE_OBSTACK
HAVE_REALLOC
HAVE_RESOLV_H
HAVE_RESTARTABLE_SYSCALLS
HAVE_ST_BLKSIZE
HAVE_ST_BLOCKS
HAVE_ST_RDEV
HAVE_STAT_EMPTY_STRING_BUG
HAVE_STDBOOL_H
HAVE_STRCOLL
HAVE_STRERROR_R
HAVE_STRFTIME
HAVE_STRINGIZE
HAVE_STRNLEN
HAVE_STRUCT_DIRENT_D_INO
HAVE_STRUCT_DIRENT_D_TYPE
HAVE_STRUCT_STAT_ST_BLKSIZE
HAVE_STRUCT_STAT_ST_BLOCKS
HAVE_STRUCT_STAT_ST_RDEV
HAVE_SYS_DIR_H
HAVE_SYS_NDIR_H
HAVE_SYS_WAIT_H
HAVE_TM_ZONE
HAVE_TYPEOF
HAVE_TZNAME
HAVE_UINT16_T
HAVE_UINT32_T
HAVE_UINT64_T
HAVE_UINT8_T
HAVE_UINTMAX_T
HAVE_UINTPTR_T
HAVE_UNSIGNED_LONG_LONG_INT
HAVE_UTIME_NULL
HAVE_VFORK_H
HAVE_VPRINTF
HAVE_WAIT3
HAVE_WORKING_FORK
HAVE_WORKING_VFORK
inline
int16_t
int32_t
int64_t
int8_t
INT_16_BITS
intmax_t
intptr_t
LONG_64_BITS
LSTAT_FOLLOWS_SLASHED_SYMLINK
MAJOR_IN_MKDEV
MAJOR_IN_SYSMACROS
malloc
mbstate_t
mode_t
NDEBUG
NDIR
NEED_MEMORY_H
NEED_SETGID
NLIST_NAME_UNION
NO_MINUS_C_MINUS_O
off_t
PACKAGE_BUGREPORT
PACKAGE_NAME
PACKAGE_STRING
PACKAGE_TARNAME
PACKAGE_VERSION
PARAMS
pid_t
PROTOTYPES
realloc
restrict
RETSIGTYPE
SELECT_TYPE_ARG1
SELECT_TYPE_ARG234
SELECT_TYPE_ARG5
SETPGRP_VOID
SETVBUF_REVERSED
size_t
ssize_t
STAT_MACROS_BROKEN
STDC_HEADERS
STRERROR_R_CHAR_P
SVR4
SYS_SIGLIST_DECLARED
SYSDIR
SYSNDIR
TIME_WITH_SYS_TIME
TM_IN_SYS_TIME
typeof
uid_t
uint16_t
uint32_t
uint64_t
uint8_t
uintmax_t
uintptr_t
UMAX
UMAX4_3
USG
vfork
volatile
WORDS_BIGENDIAN
X_DISPLAY_MISSING
YYTEXT_POINTER