Text - Character

A character is an atomic unit of text as specified by ISO/IEC 10646:2000 [ISO/IEC 10646] and is categorized as a primitive data type

A character is the smallest component of written language that has semantic value; refers to the abstract meaning and/or shape …

Characters will not appear on your screen as intended unless you have the appropriate font (that contains the appropriate glyph)

Character are the basic unit of organization of encoded text.

A character is usually represented as an Unicode code point where an int value from 0 to 65535 represents all Unicode code points, including supplementary code points.

A Character can also be simply a set of characters:

• letters,
• numbers,
• symbols (mathematical),
• ideograms,
• logograms (from non-phonetic writing systems such as kanji),
• etc…

For example, the following character set appears in several code pages:

• 26 non-accented letters A through Z ( A,B,C….X,Y,Z)
• 26 non-accented letters a through z ( a,b,c,…x,y,z)
• digits 0 through 9
• special characters: . , : ; ? ( ) ' “ / - _ & + % * = < >

• Box-drawing_character The Unicode Standard Code Charts
• Text - Non-printing Character (Tabulation, New Line, ...)
• Text - Control Characters
• …

You can type character directly from a keyboard where each key represents a character according to the keyboard layout

See Text - Encoding (Character Set|charset|code page)

Problem: Which character is –

Steps:

• The Character Set is UTF8. We got then hexadecimal in UTF8.

echo $LANG

The Hexadecimal in UTF8 of this character is e2 80 93. It corresponds to the unicode character 2013 - EN DASH. See Translation of a UTF-8 Multibyte sequence to Unicode - Example 2. 0a is the end of file.

echo – | hexdump -C

00000000  e2 80 93 0a                                       |....|
00000004

The charCodeAt() method returns the UTF-16 code unit (an integer between 0 and 65535) at the given index.

console.log('ø'.charCodeAt(0));

The character map application of windows where you can search

Character.toChars(int)[0]

For example, Character.isLetter(0x2F81A) returns true because the code point value represents a letter (a CJK ideograph).

Diff between Characters with an hex tool such as `hexdump` on Unix that output hexadecimal digits

Problem:

• Are this two characters the same ?

–
-

Steps:

• The Character Set is UTF8. We got then hexadecimal in UTF8.

echo $LANG

en_US.UTF-8

• The Hexadecimal in UTF8 of the first character is e2 80 93. It corresponds to the unicode character 2013 - EN DASH. See Translation of a UTF-8 Multibyte sequence to Unicode - Example 2. 0a is the end of file.

echo – | hexdump -C

00000000  e2 80 93 0a                                       |....|
00000004

• The Hexadecimal in UTF8 of the first character is 2d. This is the unicode character 2d - Hyphen Minus

echo  - | hexdump -C

00000000  2d 0a                                             |-.|
00000002

Each character requires:

• ASCII: one byte of memory
• Unicode - UTF8: 8 bytes

• Character
• Character Model for the World Wide Web 1.0: Fundamentals