Where Online Learning is simpler!

The C and C++ Include Header Files

cat -n /usr/include/features-time64.h

     1	/* Features part to handle 64-bit time_t support.
     2	   Copyright (C) 2021-2026 Free Software Foundation, Inc.
     3	   This file is part of the GNU C Library.
     4	
     5	   The GNU C Library is free software; you can redistribute it and/or
     6	   modify it under the terms of the GNU Lesser General Public
     7	   License as published by the Free Software Foundation; either
     8	   version 2.1 of the License, or (at your option) any later version.
     9	
    10	   The GNU C Library is distributed in the hope that it will be useful,
    11	   but WITHOUT ANY WARRANTY; without even the implied warranty of
    12	   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    13	   Lesser General Public License for more details.
    14	
    15	   You should have received a copy of the GNU Lesser General Public
    16	   License along with the GNU C Library; if not, see
    17	   <https://www.gnu.org/licenses/>.  */
    18	
    19	/* We need to know the word size in order to check the time size.  */
    20	#include <bits/wordsize.h>
    21	#include <bits/timesize.h>
    22	
    23	#if defined _TIME_BITS
    24	# if _TIME_BITS == 64
    25	#  if ! defined (_FILE_OFFSET_BITS) || _FILE_OFFSET_BITS != 64
    26	#   error "_TIME_BITS=64 is allowed only with _FILE_OFFSET_BITS=64"
    27	#  endif
    28	#  define __USE_TIME_BITS64	1
    29	# elif _TIME_BITS == 32
    30	#  if __TIMESIZE > 32
    31	#   error "_TIME_BITS=32 is not compatible with __TIMESIZE > 32"
    32	#  endif
    33	# else
    34	#  error Invalid _TIME_BITS value (can only be 32 or 64-bit)
    35	# endif
    36	#elif __TIMESIZE == 64
    37	# define __USE_TIME_BITS64      1
    38	#endif
    39	
    40	#if defined __USE_TIME_BITS64 && __TIMESIZE == 32
    41	# define __USE_TIME64_REDIRECTS 1
    42	#endif