stdbool_.h

00001 /* Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
00002    Written by Bruno Haible <haible@clisp.cons.org>, 2001.
00003 
00004    This program is free software; you can redistribute it and/or modify
00005    it under the terms of the GNU Lesser General Public License as published by
00006    the Free Software Foundation; either version 2.1, or (at your option)
00007    any later version.
00008 
00009    This program is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00012    GNU Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public License
00015    along with this program; if not, write to the Free Software Foundation,
00016    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
00017 
00018 #ifndef _STDBOOL_H
00019 #define _STDBOOL_H
00020 
00021 /* ISO C 99 <stdbool.h> for platforms that lack it.  */
00022 
00023 /* Usage suggestions:
00024 
00025    Programs that use <stdbool.h> should be aware of some limitations
00026    and standards compliance issues.
00027 
00028    Standards compliance:
00029 
00030        - <stdbool.h> must be #included before 'bool', 'false', 'true'
00031          can be used.
00032 
00033        - You cannot assume that sizeof (bool) == 1.
00034 
00035        - Programs should not undefine the macros bool, true, and false,
00036          as C99 lists that as an "obsolescent feature".
00037 
00038    Limitations of this substitute, when used in a C89 environment:
00039 
00040        - <stdbool.h> must be #included before the '_Bool' type can be used.
00041 
00042        - You cannot assume that _Bool is a typedef; it might be a macro.
00043 
00044        - In C99, casts and automatic conversions to '_Bool' or 'bool' are
00045          performed in such a way that every nonzero value gets converted
00046          to 'true', and zero gets converted to 'false'.  This doesn't work
00047          with this substitute.  With this substitute, only the values 0 and 1
00048          give the expected result when converted to _Bool' or 'bool'.
00049 
00050    Also, it is suggested that programs use 'bool' rather than '_Bool';
00051    this isn't required, but 'bool' is more common.  */
00052 
00053 
00054 /* 7.16. Boolean type and values */
00055 
00056 /* BeOS <sys/socket.h> already #defines false 0, true 1.  We use the same
00057    definitions below, but temporarily we have to #undef them.  */
00058 #ifdef __BEOS__
00059 # include <OS.h> /* defines bool but not _Bool */
00060 # undef false
00061 # undef true
00062 #endif
00063 
00064 /* For the sake of symbolic names in gdb, we define true and false as
00065    enum constants, not only as macros.
00066    It is tempting to write
00067       typedef enum { false = 0, true = 1 } _Bool;
00068    so that gdb prints values of type 'bool' symbolically. But if we do
00069    this, values of type '_Bool' may promote to 'int' or 'unsigned int'
00070    (see ISO C 99 6.7.2.2.(4)); however, '_Bool' must promote to 'int'
00071    (see ISO C 99 6.3.1.1.(2)).  So we add a negative value to the
00072    enum; this ensures that '_Bool' promotes to 'int'.  */
00073 #if !(defined __cplusplus || defined __BEOS__)
00074 # if !@HAVE__BOOL@
00075 #  if defined __SUNPRO_C && (__SUNPRO_C < 0x550 || __STDC__ == 1)
00076     /* Avoid stupid "warning: _Bool is a keyword in ISO C99".  */
00077 #   define _Bool signed char
00078 enum { false = 0, true = 1 };
00079 #  else
00080 typedef enum { _Bool_must_promote_to_int = -1, false = 0, true = 1 } _Bool;
00081 #  endif
00082 # endif
00083 #else
00084 typedef bool _Bool;
00085 #endif
00086 #define bool _Bool
00087 
00088 /* The other macros must be usable in preprocessor directives.  */
00089 #define false 0
00090 #define true 1
00091 #define __bool_true_false_are_defined 1
00092 
00093 #endif /* _STDBOOL_H */

Generated on Sun Sep 24 20:10:47 2006 for WvStreams by  doxygen 1.4.7