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 */