UTF-32和UCS-4有什么区别？ [英] What is the difference between UTF-32 and UCS-4?

问题描述

UTF-32和UCS-4有什么区别？
应该不是UTF-32是固定宽度的编码吗？

What is the difference between UTF-32 and UCS-4 ? Isn't UTF-32 supposed to be a fixed-width encoding ?

推荐答案

UTF-32 作为 UCS-4 的子集而启动。除了UTF-32标准还具有其他Unicode语义外，现在完全相同。查看有关：

UTF-32 has started as a subset of UCS-4. Now it is identical except that the UTF-32 standard has additional Unicode semantics. See details on wikipedia:

原始的 ISO 10646标准定义了一种称为
UCS-4 的31位编码形式，其中通用字符集
中的每个编码字符（UCS）由代码空间
中介于0到十六进制7FFFFFFF之间的32位友好代码值表示。

The original ISO 10646 standard defines a 31-bit encoding form called UCS-4, in which each encoded character in the Universal Character Set (UCS) is represented by a 32-bit friendly code value in the code space of integers between 0 and hexadecimal 7FFFFFFF.

因为实际上只有17个平面在使用中，所有当前代码点
在 0 和 0x10FFFF 之间。 UTF-32是UCS-4的子集，该范围仅使用
。由于JTC1 / SC2 / WG2的
原则和程序文件规定，将来所有字符分配都将
限制在BMP或前14个辅助飞机上，因此UTF-32
将能够代表所有Unicode字符。因此， UCS-4
和UTF-32现在相同，除了UTF-32标准具有
个额外的Unicode语义。

Because only 17 planes are actually in use, all current code points are between 0 and 0x10FFFF. UTF-32 is a subset of UCS-4 that uses only this range. Since the Principles and Procedures document of JTC1/SC2/WG2 states that all future assignments of characters will be constrained to the BMP or the first 14 supplementary planes, UTF-32 will be able to represent all Unicode characters. Accordingly, UCS-4 and UTF-32 are now identical except that the UTF-32 standard has additional Unicode semantics.

但是，我不确定，其他Unicode语义是什么意思。也许有人可以提供更好的答案。

However, I am not exactly sure, what additional Unicode semantics means. Maybe someone can provide a better answer.

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