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.. highlight:: cpp
.. _lang-modulo:
Modulo Operator (``%``)
=======================
Calculates the `remainder <http://en.wikipedia.org/wiki/Remainder>`_
when one integer is divided by another. It is useful for keeping a
variable within a particular range (e.g. the size of an array).
Syntax
------
::
dividend % divisor
Parameters
----------
**dividend**: the number to be divided
**divisor**: the number to divide by
Returns
-------
The remainder of **dividend**\ /\ **divisor**\ .
Examples
--------
::
int x;
x = 7 % 5; // x now contains 2
x = 9 % 5; // x now contains 4
x = 5 % 5; // x now contains 0
x = 4 % 5; // x now contains 4
::
/* update one value in an array each time through a loop */
int values[10];
int i = 0;
void setup() {
// no setup necessary
}
void loop() {
values[i] = analogRead(0);
i = (i + 1) % 10; // modulo operator makes sure i stays between 0 and 9
}
Tip
---
The modulo operator does not work on floats. For that, you can use
the C standard library function `fmod()
<http://sourceware.org/newlib/libm.html#fmod>`_.
See Also
--------
- :ref:`Arithmetic <lang-arithmetic>`
.. include:: /arduino-cc-attribution.txt
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