L013 | ASCII Code Explained | Class 9th | ICSE | Computer Applications | Java

L014 | Unicode Explained | ASCII vs Unicode | Class 9th | ICSE | Computer Applications | Java

Character Set in Java

Character Set refers to the collection of characters that a programming language can recognize and process. In Java, characters include letters, digits, punctuation marks, special symbols, and control characters. Every character has a unique code, enabling computers to store and manipulate text.

Types of Character Sets

Different character sets are used in computing to represent a wide range of characters from various languages and symbols. The most common ones include:

1. ASCII (American Standard Code for Information Interchange):
   • ASCII is one of the earliest character encoding standards, developed to represent text in computers and other devices.
   • It uses 7 bits to represent each character, allowing for 128 unique characters. These include:
     • Uppercase and lowercase English letters (A-Z, a-z)
     • Digits (0-9)
     • Basic punctuation (e.g., !, @, #, %)
     • Control characters (e.g., newline, tab)
   • ASCII is widely used in English-based systems, but its limitations restrict it from covering other languages.
2. Extended ASCII:
   • Extended ASCII uses 8 bits (1 byte), providing 256 unique characters. This includes all standard ASCII characters plus extra characters used in various European languages (e.g., accented letters).
   • It’s still limited compared to modern character sets, as it only covers characters in the Latin alphabet.

ASCII Code

ASCII stands for American Standard Code for Information Interchange and is primarily used to encode English characters. ASCII assigns a unique numerical code to each character, which is stored in binary form.

• 7-bit Encoding: ASCII uses 7 bits, allowing for 128 characters (0 to 127).
• Character Mapping:
  • A to Z corresponds to codes 65 to 90.
  • a to z corresponds to codes 97 to 122.
  • 0 to 9 corresponds to codes 48 to 57.
  • Punctuation marks, such as !, ?, @, and others, have unique codes.
• Control Characters: ASCII includes special codes for control characters like newline (10), carriage return (13), and tab (9).

Example: In ASCII,

• The character A is represented by the binary code 1000001 (decimal 65).
• The character a is represented by 1100001 (decimal 97).

While ASCII is sufficient for English text, it lacks the capability to represent characters from other languages.

Unicode (Universal Character Encoding Standard)

Unicode was developed to overcome the limitations of ASCII by creating a universal standard for encoding text, encompassing nearly every written language, symbol, and emoji. It assigns a unique code to each character across all scripts, making it ideal for international applications.

• Code Points: Unicode uses a code point system, which assigns a unique number to every character in the Unicode standard.
  • Example: The letter A in Unicode is U+0041, where U+ denotes a Unicode code point.