Introduction to Character Representation

ASCII (American Standard Code for Information Interchange)

• ASCII is a 7-bit character encoding standard that represents 128 characters.
• It includes uppercase and lowercase English letters, digits, punctuation symbols, and control characters.
• Example: The character 'A' is represented by the binary value 1000001 (decimal 65).

CopyDecimal  Binary    Character
-------  ------    ---------
    65   1000001   A
    66   1000010   B
    67   1000011   C
   ...   ...       ...

Extended ASCII

• Extended ASCII is an 8-bit character encoding that extends the original ASCII to represent 256 characters.
• It includes additional characters like accented letters, symbols, and box-drawing characters.
• The first 128 characters are the same as standard ASCII.
• However, the characters in the extended ASCII range (128-255) are not standardized and may vary between different code pages.
• Example: The character 'ç' (c with cedilla) is represented by the binary value 10000111 (decimal 135) in the Windows-1252 code page, but it may have a different representation in other extended ASCII code pages.

Unicode

• Unicode is a universal character encoding standard that aims to represent all characters from all writing systems.
• It supports over 143,000 characters across multiple languages and scripts, including characters with diacritics like 'á'.
• Unicode has several encoding forms, including UTF-8, UTF-16, and UTF-32.
• UTF-8 is the most common encoding on the web. It uses 1 to 4 bytes to represent a character.
• Example: The character 'á' (a with acute accent) is represented by the bytes 11000011 10100001 (UTF-8) or the code point U+00E1.

Conclusion