ASCII 和 Unicode 有什么区别? [英] What's the difference between ASCII and Unicode?

问题描述

Unicode 和 ASCII 的确切区别是什么?

What's the exact difference between Unicode and ASCII?

ASCII 共有 128 个字符(扩展集中的 256 个字符).

ASCII has a total of 128 characters (256 in the extended set).

Unicode 字符有大小规范吗?

Is there any size specification for Unicode characters?

推荐答案

ASCII 定义了 128 个字符，映射到数字 0–127.Unicode 定义(小于)2²¹ 个字符，类似地，这些字符映射到数字 0–2²¹(尽管当前并非所有数字都已分配，有些数字已保留).

ASCII defines 128 characters, which map to the numbers 0–127. Unicode defines (less than) 2²¹ characters, which, similarly, map to numbers 0–2²¹ (though not all numbers are currently assigned, and some are reserved).

Unicode 是 ASCII 的超集，数字 0–127 在 ASCII 中的含义与在 Unicode 中的含义相同.例如，数字 65 的意思是拉丁大写的‘A’".

Unicode is a superset of ASCII, and the numbers 0–127 have the same meaning in ASCII as they have in Unicode. For example, the number 65 means "Latin capital 'A'".

由于 Unicode 字符通常不适合一个 8 位字节，因此有多种以字节序列存储 Unicode 字符的方法，例如 UTF-32 和 UTF-8.

Because Unicode characters don't generally fit into one 8-bit byte, there are numerous ways of storing Unicode characters in byte sequences, such as UTF-32 and UTF-8.

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