Characters and Strings

Text in character arrays and string arrays

Character arrays and string arrays provide storage for text data in MATLAB^®.

A character array is a sequence of characters, just as a numeric array is a sequence of numbers. A typical use is to store short pieces of text as character vectors, such as c = 'Hello World'.
A string array is a container for pieces of text. String arrays provide a set of functions for working with text as data. You can create strings using double quotes, such as str = "Greetings friend". To convert data to string arrays, use the string function.

For more information, see Text in String and Character Arrays or watch Using String Arrays for Text Data.

Functions

Create, Concatenate, and Convert

String Arrays

`string`	String array
`strings`	Create string array with no characters
`join`	Combine strings
`plus`	Add numbers, append strings

Character Arrays

`char`	Character array
`cellstr`	Convert to cell array of character vectors
`blanks`	Create character array of blanks
`newline`	Create newline character

Character or String Arrays

`compose`	Format data into multiple strings
`sprintf`	Format data into string or character vector
`strcat`	Concatenate strings horizontally
`append`	Combine strings

Convert Input Arguments

`convertCharsToStrings`	Convert character arrays to string arrays, leaving other arrays unaltered
`convertStringsToChars`	Convert string arrays to character arrays, leaving other arrays unaltered
`convertContainedStringsToChars`	Convert string arrays at any level of cell array or structure

Convert Between Numeric and Strings

`double`	Double-precision arrays
`string`	String array
`str2double`	Convert strings to double precision values
`num2str`	Convert numbers to character array

Determine Type and Properties

Data Type

`ischar`	Determine if input is character array
`iscellstr`	Determine if input is cell array of character vectors
`isstring`	Determine if input is string array
`isStringScalar`	Determine if input is string array with one element

Text Properties

`strlength`	Lengths of strings
`isstrprop`	Determine which characters in input strings are of specified category
`isletter`	Determine which characters are letters
`isspace`	Determine which characters are space characters

Find and Replace

Find

`contains`	Determine if pattern is in strings
`matches`	Determine if pattern matches strings
`count`	Count occurrences of pattern in strings
`endsWith`	Determine if strings end with pattern
`startsWith`	Determine if strings start with pattern
`strfind`	Find strings within other strings
`sscanf`	Read formatted data from strings

Replace

`replace`	Find and replace one or more substrings
`replaceBetween`	Replace substrings between start and end points
`strrep`	Find and replace substrings

Match Patterns

Building Patterns

pattern Patterns to search and match text (Since R2020b)

Character-Matching Patterns

`alphanumericsPattern`	Match letter and digit characters (Since R2020b)
`characterListPattern`	Match characters from list (Since R2020b)
`digitsPattern`	Match digit characters (Since R2020b)
`lettersPattern`	Match letter characters (Since R2020b)
`whitespacePattern`	Match whitespace characters (Since R2020b)
`wildcardPattern`	Matches as few characters of any type (Since R2020b)

Pattern Search Rules

`optionalPattern`	Make pattern optional to match (Since R2020b)
`possessivePattern`	Match pattern without backtracking (Since R2020b)
`caseSensitivePattern`	Match pattern with case sensitivity (Since R2020b)
`caseInsensitivePattern`	Match pattern regardless of case (Since R2020b)
`asFewOfPattern`	Match pattern as few times as possible (Since R2020b)
`asManyOfPattern`	Match pattern as many times as possible (Since R2020b)

Boundary Patterns

`alphanumericBoundary`	Match boundary between alphanumeric and non-alphanumeric characters (Since R2020b)
`digitBoundary`	Match boundary between digit characters and non-digit characters (Since R2020b)
`letterBoundary`	Match boundary between letter characters and non-letter characters (Since R2020b)
`whitespaceBoundary`	Match boundary between whitespace characters and non-whitespace characters (Since R2020b)
`lineBoundary`	Match start or end of line (Since R2020b)
`textBoundary`	Match start or end of text (Since R2020b)
`lookAheadBoundary`	Match boundary before specified pattern (Since R2020b)
`lookBehindBoundary`	Match boundary following specified pattern (Since R2020b)

Custom Pattern Display

`maskedPattern`	Pattern with specified display name (Since R2020b)
`namedPattern`	Designate named pattern (Since R2020b)

Regular Expressions

`regexp`	Match regular expression (case sensitive)
`regexpi`	Match regular expression (case insensitive)
`regexprep`	Replace text using regular expression
`regexptranslate`	Translate text into regular expression
`regexpPattern`	Pattern that matches specified regular expression (Since R2020b)

Join and Split

`join`	Combine strings
`plus`	Add numbers, append strings
`split`	Split strings at delimiters
`splitlines`	Split strings at newline characters
`strjoin`	Join strings in array
`strsplit`	Split string or character vector at specified delimiter
`strtok`	Selected parts of strings
`extract`	Extract substrings from strings (Since R2020b)
`extractAfter`	Extract substrings after specified positions
`extractBefore`	Extract substrings before specified positions
`extractBetween`	Extract substrings between start and end points

Edit

`erase`	Delete substrings within strings
`eraseBetween`	Delete substrings between start and end points
`extract`	Extract substrings from strings (Since R2020b)
`extractAfter`	Extract substrings after specified positions
`extractBefore`	Extract substrings before specified positions
`extractBetween`	Extract substrings between start and end points
`insertAfter`	Insert strings after specified substrings
`insertBefore`	Insert strings before specified substrings
`pad`	Add leading or trailing characters to strings
`strip`	Remove leading and trailing characters from strings
`lower`	Convert strings to lowercase
`upper`	Convert strings to uppercase
`reverse`	Reverse order of characters in strings
`deblank`	Remove trailing whitespace from ends of strings
`strtrim`	Remove leading and trailing whitespace from strings
`strjust`	Justify strings

Compare

`matches`	Determine if pattern matches strings
`strcmp`	Compare strings
`strcmpi`	Compare strings (case insensitive)
`strncmp`	Compare first `n` characters of strings (case sensitive)
`strncmpi`	Compare first `n` characters of strings (case insensitive)

Topics

Text in String and Character Arrays

Store and manipulate text using either string arrays or character arrays.
Analyze Text Data with String Arrays

This example shows how to analyze text data with string arrays. It shows how to store, split, and sort text, and how to compute and collect statistics for text in a string array.
- Compare Text
- Test for Empty Strings and Missing Values
Formatting Text
Compose character arrays or string arrays that include ordinary text and data formatted to your specification.
Search and Replace Text

MATLAB provides several functions to search for, replace, or extract text in string arrays and character vectors.
- Build Pattern Expressions
- Regular Expressions
- Lookahead Assertions in Regular Expressions
- Tokens in Regular Expressions
- Dynamic Regular Expressions
Unicode and ASCII Values
MATLAB stores all characters as Unicode characters. Both strings and character vectors use the same encoding. You can convert characters to their Unicode code values, and numbers to characters.
Hexadecimal and Binary Values
Specify hexadecimal and binary values either as literals or as text. Hexadecimal and binary literals are stored as integers. You can convert text representing hexadecimal and binary values to numbers, and numbers to text representations.

Related Information

Fundamentals of Programming (MathWorks Teaching Resources)