Matlab Types - Character

Character

• In MATLAB, characters and numeric values share equal status. Each character is stored in Unicode and occupies 2 bytes
  • Internally, character operations are really operations on the numeric code points; a character is essentially a numeric string
  • Hence MATLAB can be said to have only one fundamental data structure: the numeric array
  • Consequently, most functions that accept numeric arguments also accept character arguments
• Newer versions add the string type, better suited to string manipulation; for the main differences from char, see Matlab Characters and Strings

Properties

• Unlike numeric data, where a single value of any precision has length 1, every single character has length 1
  • length(1200+3.123i) = 1; length('hello') = 5
• Identity test functions
  • ischar: is the input a char?
  • isletter returns a logical array of the same size, indicating whether each element is an English letter
  • isspace returns a logical array of the same size, indicating whether each element is a whitespace character
  • isstrprop
• The function double converts a character to its ASCII code point

Creation and Concatenation

• The most basic syntax wraps the characters in single quotes ': 'string'
  • Note that double quotes " create a string instead
  • A literal single quote is written as ''
    • e.g. 'I''m Josh' = 'I'm Josh'

Single-Row Character Arrays

To horizontally concatenate a = 'hello,', b = ' this ', c = 'world!' into a single-row string:

• Use brackets []
  • [a b c] = 'hello, this world!'
• Function strcat(a,b,c) = 'hello, world'
  • strcat automatically removes trailing whitespace characters
    • whitespace includes space, tab, newline, carriage return, etc.

Multi-Row Character Arrays

A multi-row character array is a 2-D character array; it is built by vertically concatenating character arrays of the same length:

• Inside [], separate rows with ;
  • [a;b;c]
• Function char: char(a,b,c)
  • Pads any empty array so the rows align
• Function strvcat(a,b,c)
  • Not recommended
  • Same usage as char(a,b,c), except empty arrays are skipped (removed)

Special Character Arrays

• Function blanks(n) — creates a row vector of n space characters

Comparison

• Equality

Search and Replace

A

Related functions:

• strrep
• strfind
• findstr
• strmatch
• strok