The C and C++ Include Header Files

/usr/include/x86_64-linux-gnu/bits/wchar.h


$ cat -n /usr/include/x86_64-linux-gnu/bits/wchar.h

     1	/* wchar_t type related definitions.
     2	   Copyright (C) 2000-2024 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	#ifndef _BITS_WCHAR_H
    20	#define _BITS_WCHAR_H	1
    21	
    22	/* The fallback definitions, for when __WCHAR_MAX__ or __WCHAR_MIN__
    23	   are not defined, give the right value and type as long as both int
    24	   and wchar_t are 32-bit types.  Adding L'\0' to a constant value
    25	   ensures that the type is correct; it is necessary to use (L'\0' +
    26	   0) rather than just L'\0' so that the type in C++ is the promoted
    27	   version of wchar_t rather than the distinct wchar_t type itself.
    28	   Because wchar_t in preprocessor #if expressions is treated as
    29	   intmax_t or uintmax_t, the expression (L'\0' - 1) would have the
    30	   wrong value for WCHAR_MAX in such expressions and so cannot be used
    31	   to define __WCHAR_MAX in the unsigned case.  */
    32	
    33	#ifdef __WCHAR_MAX__
    34	# define __WCHAR_MAX	__WCHAR_MAX__
    35	#elif L'\0' - 1 > 0
    36	# define __WCHAR_MAX	(0xffffffffu + L'\0')
    37	#else
    38	# define __WCHAR_MAX	(0x7fffffff + L'\0')
    39	#endif
    40	
    41	#ifdef __WCHAR_MIN__
    42	# define __WCHAR_MIN	__WCHAR_MIN__
    43	#elif L'\0' - 1 > 0
    44	# define __WCHAR_MIN	(L'\0' + 0)
    45	#else
    46	# define __WCHAR_MIN	(-__WCHAR_MAX - 1)
    47	#endif
    48	
    49	#endif	/* bits/wchar.h */