- A bit is the smallest unit of storage that can have a value of 0 or 1. 8 bits make up 1 byte. - A byte is a group of 8 bits that can represent numbers from 0-255. Storage size is measured in bytes, with prefixes like KB, MB, GB, and TB. - Characters are represented by code points that have values from 0 to over 1 million. Character encoding maps code points to bytes for storage in memory, with UTF-8 being the most common encoding.

1. Bits, Bytes and
Characters
Shaikhul Islam Chowdhury
dev.to/shaikhul
github.com/shaikhul

2. Bit
● Smallest unit of storage
● Bit is 0 or 1
● 8 bits - 1 Byte

3. Byte
● Group of 8 bit
● 1 bit pattern - 0, 1 - 2 entry
● 2 bit pattern - 00, 01, 10, 11 - 4 entry
● n bit - 2^n entry possible
● 1 Byte
○ 8 bit - 2^8 - 255 entry
○ Can hold 0 - 255 numbers

4. Bytes
● How many bytes?
● All storage are measured in Bytes
● Bigger units
○ KB (1000 B),
○ MB (1000 KB),
○ GB (1000 MB),
○ TB (1000 GB) etc

5. Character and Unicode
● Characters are represented as code point - range 0 - 0x10FFFF ( 1 million)
Character Unicode Code Point Glyph
Latin small letter a 0x61 a
Black chess knight 0x265E ♞
Euro currency 0x20AC €

6. Character and Unicode (Code Point)
Python
In [22]: chr(0x0041)
Out[22]: 'A'
In [23]: chr(0x00df)
Out[23]: 'ß'
In [24]: chr(0x6771)
Out[24]: '東'
In [25]: chr(0x10400)
Out[25]: '𐐀'
Java
jshell> new String(Character.toChars(0x0041))
$13 ==> "A"
jshell> new String(Character.toChars(0x00df))
$14 ==> "ß"
jshell> new String(Character.toChars(0x6771))
$15 ==> "東"
jshell> new String(Character.toChars(0x10400))
$16 ==> "𐐀"

7. (Character) Encoding
● Unicode string is a sequence of code points (limit 0 - 0x10FFFF)
● character encoding - translate sequence of code points into Bytes to store into memory
○ ASCII: 7 bit (0 - 127), english letters
○ UTF-8: most common, default in python
○ UTF-16 etc

8. (Character) Encoding - String to Bytes
Python
In [40]: c = chr(0x20ac)
In [41]: c
Out[41]: '€'
In [42]: c.encode('utf-8')
Out[42]: b'xe2x82xac'
Java
jshell> String str = new String(Character.toChars(0x20ac))
str ==> "€"
jshell> import java.nio.charset.*
jshell> byte bytes[] = str.getBytes(StandardCharsets.UTF_8)
bytes ==> byte[3] { -30, -126, -84 }
jshell> for (byte b: bytes) { System.out.printf("%x ", b); }
e2 82 ac

9. References
● Stanford CS 101 on Bits and Bytes
● Unicode HOWTO — Python 3.9.1 documentation
● Unicode (The Java™ Tutorials > Internationalization > Working with Text)

10. Thank You