是否保证char是8位长？ [英] Is char guaranteed to be exactly 8-bit long?
问题描述
这就是。
推荐答案
从 ANSI C规范的副本，请参见第3.1.2.5节 - 类型： p>
From a copy of the ANSI C specification, see Section 3.1.2.5 - Types:
声明为char类型的对象是
，足够大到存储
的任何成员基本执行字符集。如果
$ 2.2.1中枚举的所需源
字符集的成员是存储在char对象中的
，则其值为
，保证为正值。如果其他
数量存储在char
对象中，则行为是
实现定义的：值为
被视为signed或
非负整数。 p>
An object declared as type char is large enough to store any member of the basic execution character set. If a member of the required source character set enumerated in $2.2.1 is stored in a char object, its value is guaranteed to be positive. If other quantities are stored in a char object, the behavior is implementation-defined: the values are treated as either signed or nonnegative integers.
执行字符集的概念在第2.2.1节 - 字符集中引入。
The concept of "execution character set" is introduced in Section 2.2.1 - Character sets.
换句话说，char必须至少足够大以包含至少95个不同字符的编码，这些字符组成基本执行字符集。
In other words, a char has to be at least big enough to contain an encoding of at least the 95 different characters which make up the basic execution character set.
现在添加到部分
$ < b $ b符合的实现应该
记录在
本节中指定的所有限制，这将在头< limits.h>中指定和
。
< float.h>。
整数类型的大小
下面给出的值应为
由常量表达式替换
适用于#if预处理
指令。它们的
实现定义的值应该是
等于或大于等于
（绝对值）的那些值，而
是相同的符号。
The values given below shall be replaced by constant expressions suitable for use in #if preprocessing directives. Their implementation-defined values shall be equal or greater in magnitude (absolute value) to those shown, with the same sign.
-
最小的最大位数
不是位字段的对象
（字节）
CHAR_BIT 8
maximum number of bits for smallest object that is not a bit-field (byte)
CHAR_BIT 8
类型
的对象的最小值已签署字符
SCHAR_MIN -127
minimum value for an object of type
signed char
SCHAR_MIN -127
类型的对象的最大值
签名的字符
SCHAR_MAX +127
maximum value for an object of type
signed char
SCHAR_MAX +127
类型的对象的最大值unsigned char
UCHAR_MAX 255
maximum value for an object of type
unsigned char
UCHAR_MAX 255
....
所以你有它 - 一个字符的位数必须至少为8。
So there you have it - the number of bits in a char must be at least 8.
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