Unicode

Unicode is a standard for text encoding.
It defines a mapping of integers to characters in various languages (code-points).
Various text-encodings alter how the integer is divided across byte(s),
but regardless of it's composition, the assigned number/character is constant.

For example, UTF-8 uses the first 1-5 bits of a byte to indicate the type of byte, and if the number spans multiple bytes.
The remaining bits are assembled into one large integer, that refers to a code-point/character.

UTF-1,7,8,16,32 all map to the same character set defined by unicode.

Documentation

wikipedia: unicode	https://en.wikipedia.org/wiki/Unicode
wikipedia: utf-8	https://en.wikipedia.org/wiki/UTF-8

Encodings

UTF-1

UTF-7

UTF-8

Predominantly used by the internet (since reverse-compatible with ascii, which much internet was written to support).

• reverse compatible with ASCII
• multiple bytes may be used for characters (1-4 bytes may be used)
• UTF-8 is extendable, we can add a 5th byte later if we need it.

01111111  # ascii only uses 7-bits, the leading bit is always 0
1.......  # utf-8 puts a '1' in the leading bit to indicate a multi-byte character

# the number of leading '1's in the first byte of a multi-byte character
# indicates how many following bytes will be used to represent the character
# (this one will have 3x bytes after it)
1110....  

# each following byte will have the prefix '10', indicating it is a 'continuation byte'
10......

# a byte beginning with '0' indicates this is ascii, and no following bytes are required
0.......

When looking up a multibyte character, all bytes are combined into one very large binary integer.

#  byte-1      byte-2       byte-3      byte-4
[1110]1001  [10]100100]   [10]010010  [10]000000

# combine to the binary number
1001 100100 010010 000000
1001100100010010000000

# in decimal
2507904

UTF-16

Used by windows.

UTF-32