Unicode

§什么是unicode

He explained that "[t]he name 'Unicode' is intended to suggest a unique, unified, universal encoding".

§为何出现unicode

Unicode could be roughly described as "wide-body ASCII" that has been stretched to 16 bits to encompass the characters of all the world's living languages.

§能够定义多少字符

Unicode defines a codespace of 1,114,112 code points in the range 0hex to 10FFFFhex.
256 * 256 * 17 = 1,114,111
0000 0000 0000 0000 0000 0000
0001 0000 1111 1111 1111 1111
0x10 = 16 算上0x00 一共能够表示17个平面

§什么是BMP

Basic Multilingual Plane
Plane0
0000-FFFF
这是最初的，其余的均为扩展平面

§为什么会产生utf-8,utf-16和utf-32

By early 1992, the search was on for a good byte-stream encoding of multi-byte character sets.