.. include:: ../replace.txt

.. _strings:

Text Strings in MATLAB
====================================

.. index:: text, string, cell array

We have already passed textual data to functions. Actually, what we have used
so far are called character arrays where each string is inside a pair of single
quote marks, ``'Hello world'``. Character arrays have always been a part of
|M|. But starting with version version R2016b and enhanced in version
R2017a, |M| has supported a new data type of string arrays. String arrays
are created with either double quote marks ``"My String"`` or with the
`string()` function.  String arrays have many more functions to aid in
manipulating textual data.

We might want to store a sequence of individual strings in a single array.
Look at the following code to see a problem with doing so with character arrays
and how strings and cell arrays provide solutions to the problem.

::

    >> months1to3 = ['Jan', 'Feb', 'Mar']
    months1to3 =
        'JanFebMar'
    >> months3 = ["January", "February", "March"];
    >> months3
    months3 = 
      1x3 string array
        "January"    "February"    "March"
    >> CellMonths1to3 = {'January', 'February', 'March'}
    CellMonths1to3 =
      1x3 cell array
        'January'    'February'    'March'

|M| arrays of character arrays concatenate the string elements, which in
some cases data is fine, but often is a problem. For this reason, we often
include spaces as part of character arrays, such as when we use `disp`
to combine textual and numeric data displayed to the user::

    disp(['The answer is: ', num2str(x)])

.. seealso::

    Read the |M| documentation about `Characters and Strings
    <https://www.mathworks.com/help/matlab/characters-and-strings.html>`_.

One solution for passing textual data to functions is to use a cell array to
store the data. Cell arrays are created with curly brackets ``{ }`` instead of
square arrays used for numeric arrays ``[ ]``.

A good application for using cell arrays is to set the tick labels on the
axis of a plot. See :ref:`ticks`.

.. note::

    Cell arrays are used to store many types of data besides strings. In
    terms of how cell arrays are used in |M|, you can think of a cell
    array as an array of pointers as you might have in a C language program.

.. raw:: latex

    \clearpage