什么是超长格式/编码? [英] What is exactly an overlong form/encoding?

问题描述

阅读有关UTF-8的维基百科文章，我一直在想词超长.该术语使用了很多次，但本文并未提供其含义的定义或参考.

我想知道是否有人可以解释该术语及其目的.

解决方案

这是对代码点的编码，该代码点占用了比所需更多的代码单元.

例如，U + 0020在UTF-8中由单个字节0x20表示.如果以常规方式解码两个字节0xc0 0xa0，您仍将返回U + 0020，但这是无效的表示形式.

Unicode更正#1 具有更多信息，尤其是有关表3.1B的信息./p>

Reading the Wikipedia article on UTF-8, I've been wondering about the term overlong. This term is used various times but the article doesn't provide a definition or reference for its meaning.

I would like to know if someone can explain the term and its purpose.

解决方案

It's an encoding of a code point which takes more code units than it needs to.

For example, U+0020 is represented in UTF-8 by the single byte 0x20. If you decode the two bytes 0xc0 0xa0 in the normal fashion, you'll still end up back at U+0020, but that's an invalid representation.

The Unicode Corrigendum #1 has more information, particularly around table 3.1B.

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