https://www.ruanyifeng.com/blog/2007/10/ascii_unicode_and_utf-8.html

阮一峰科普文，讲的浅显易懂

https://en.wikipedia.org/wiki/UTF-8

https://home.unicode.org/

https://www.ietf.org/rfc/rfc3629.txt

曹的unicode point：26361
utf8编码： 11100110 10011011 10111001

• ascii字符占1byte，utf8编码与ascii编码一致
• 多字节时 首字节 连续1的个数代表占用字节数；后面的字节 10开头
• 1110xxxx 10xxxxxx 10xxxxxx x代表有效数据位
• utf8是最常见的变字长编码，占1~4字节
• unicode是编码标准；utf8是unicode的存储编码实现方式，其它还有utf16, utf32等编码方式

The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)