Acquaintance encoding format

Encoding format

1. The earliest this code: ASCII code contains only: letters, numbers, special characters

   0000 0001

   0000 0101 ...

   The leftmost bit is 0 is reserved

   8bit == 1byte

   Only represent 128 different characters

2. GBK (GB): contains ASCII + Chinese

   A letter: 1byte 0000 0001

   A Chinese: 2byte 0000 0001 0100 0001

   2 ^ 16 = 65535

   Up to 65,535 characters represent

3. Unicode Unicode: all the text in the world to record the password in this

   At first: a byte to represent characters 2byte

   A letter: 0,000,000,100,000,011

   A Chinese: 0,000,000,100,000,000

   Because: Japanese Kanji 9W + 12W +

   Later: a byte character 4byte

   A letter: 0,000,000,100,000,011 0,000,000,100,000,011

   A Chinese character: 0,000,000,100,000,011 0,000,000,100,000,011

   ⬆ waste of space waste of resources

4. UTF-8: 8bit 1 with a minimum of bytes to represent a character.

   English one byte 0000 0011

   0,000,001,100,000,011 bytes Europe 2

   0000 0011 0,000,001,100,000,011 Chinese: 3 bytes

eg.   '中国12ab' :  GBK : 8byte 

​     '中国12ab' ：UTF-8：10byte

8 bit = 1byte 

1024 byte = 1Kb

1024 Kb = 1Mb 

1024 Mb = 1Gb

1024 GB = 1TB

MB to bit :

7.6MB ---> 7.6* 1024 * 1024 * 8= 63753420.8 (bit)