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+.. highlight:: cpp
+
+.. _lang-static:
+
+``static``
+==========
+
+The ``static`` keyword can be used to create variables that are
+visible to only one function. However, unlike local variables that get
+created and destroyed every time a function is called, ``static``
+variables persist beyond the function call, preserving their data
+between function calls.
+
+Variables declared as ``static`` will only be created and initialized
+the first time a function is called.
+
+.. note:: This is only one use of the ``static`` keyword in C++. It
+ has some other important uses that are not documented here; consult
+ a reliable C++ reference for details.
+
+Example
+-------
+
+One use case for ``static`` variables is implementing counters that
+last longer than the functions which need them, but shouldn't be
+shared to other functions. Here's an example::
+
+ void setup() {
+ SerialUSB.begin();
+ }
+
+ void loop() {
+ int reading;
+ if (timeToReadSensors()) {
+ reading = readSensors();
+ }
+ // do something with reading
+ }
+
+ int readSensors() {
+ static int numSensorReadings = 0;
+ numSensorReadings++;
+ if (numSensorReadings % 100 == 0) {
+ SerialUSB.print("just got to another 100 sensor readings");
+ }
+ return analogRead(...);
+ }
+
+In this example, the static variable ``numSensorReadings`` is
+initialized to zero the first time ``readSensors()`` is called, and
+then incremented, so it starts out at one. Subsequent calls to
+``readSensors()`` won't reset ``numSensorReadings`` to zero, because
+it was declared ``static``. Thus, ``numSensorReadings`` is a count of
+the number of times that ``readSensors()`` has been called.
+
+
+.. include:: cc-attribution.txt