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.. _arduino-switchcase:
switch / case statements
========================
Like :ref:`if/else <arduino-else>` blocks, A ``switch`` statement
controls program flow by allowing you to specify different code that
should be executed under various cases.
Syntax
------
::
switch (var) {
case val1:
// statements
break;
case val2:
// statements
break;
...
default:
// statements
}
Where ``var`` is a variable whose value to investigate, and the
``val1``, ``val2`` after each ``case`` are constant values that
``var`` might be.
Description
-----------
A ``switch`` statement compares the value of a variable to the values
specified in ``case`` statements. When a ``case`` statement is found
whose value matches that of the variable, the code in that case
statement is run.
The ``break`` keyword exits the switch statement, and is typically
used at the end of each ``case``. Without a ``break``, the ``switch``
statement will continue executing the following ``case`` expressions
("falling-through") until a ``break`` (or the end of the switch
statement) is reached.
Writing ``default:`` instead of a ``case`` statement allows you to
specify what to do if none of the ``case`` statements matches. Having
a ``default:`` is optional (you can leave it out), but if you have
one, it must appear after all of the ``case`` statements, as shown
above.
``switch`` statements are often used with an ``enum`` value as the
variable to compare. In this case, you can write down all of the
values the ``enum`` takes as ``case`` statements, and be sure you've
covered all the possibilities.
Example
-------
::
switch (var) {
case 1:
//do something when var equals 1
break;
case 2:
//do something when var equals 2
break;
default:
// if nothing else matches, do the default
// default is optional
}
See also:
---------
`if...else <http://arduino.cc/en/Reference/Else>`_
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