§什么是unicode
He explained that "[t]he name 'Unicode' is intended to suggest a unique, unified, universal encoding".
§为什么出现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.
§可以定义多少字符
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 一共可以表示17个平面
§什么是BMP
Basic Multilingual Plane
Plane0
0000-FFFF
这是最初的，其他的均为扩展平面
§为何会产生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.