The recommended way to create an empty string array is to use the strings function, specifying 0
as at least one of the input arguments. The isempty function returns 1 when the input is an empty
string array.
str = strings(0);
tf = isempty(str)
The strlength function returns a numeric array that is the same size as the input string array. If the
input is an empty string array, then strlength returns an empty array.
str = strings(0);
L = strlength(str)
Check for Missing Strings
String arrays also can contain missing strings. The missing string is the string equivalent to NaN for
numeric arrays. It indicates where a string array has missing values. The missing string displays as
, with no quotation marks.
You can create missing strings using the missing function. The recommended way to check for
missing strings is to use the ismissing function.
str = string(missing);
tf = ismissing(str)
Note Do not check for missing strings by comparing a string to the missing string.
The missing string is not equal to itself, just as NaN is not equal to itself.
str = string(missing);
f = (str == missing)
Terminology for Character and String Arrays
MathWorks documentation uses these terms to describe character and string arrays. For consistency,
use these terms in your own documentation, error messages, and warnings.
• Character vector — 1-by-n array of characters, of data type char.
• Character array — m-by-n array of characters, of data type char.
• Cell array of character vectors — Cell array in which each cell contains a character vector.
• String or string scalar — 1-by-1 string array. A string scalar can contain a 1-by-n sequence of
characters, but is itself one object. Use the terms "string scalar" and "character vector" alongside
each other when to be precise about size and data type. Otherwise, you can use the term "string"
in descriptions.
• String vector — 1-by-n or n-by-1 string array. If only one size is possible, then use it in your
description. For example, use "1-by-n string array" to describe an array of that size.
• String array — m-by-n string array.
• Empty string — String scalar that has no characters.
• Empty string array — String array with at least one dimension whose size is 0.
• Missing string — String scalar that is the missing value (displays as ).
6 Characters and Strings
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