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diff --git a/docs/source/lang/api/random.rst b/docs/source/lang/api/random.rst new file mode 100644 index 0000000..9875ee6 --- /dev/null +++ b/docs/source/lang/api/random.rst @@ -0,0 +1,71 @@ +.. highlight:: cpp + +.. _lang-random: + +random() +======== + +The ``random()`` function generates pseudo-random numbers. + +Library Documentation +--------------------- + +.. FIXME [Breathe] use doxygenfunction when possible + +.. cpp:function:: random(long max) + + Same as a call to ``random(0, max)``. + +.. cpp:function:: random(long min, long max) + + Generate a pseudo-random number with given lower and upper bounds. + + *Parameters* + + - ``min`` - Lower bound on the returned value, inclusive + - ``max`` - Upper bound on the returned value, exclusive + + *Returns*: A pseudo-random number in the range [min, max). + +Discussion +---------- + +If it is important for a sequence of values generated by +:ref:`random() <lang-random>` to differ, on subsequent executions of a +sketch, use :ref:`randomSeed() <lang-randomseed>` to initialize the +random number generator with a fairly random input, such as +:ref:`analogRead() <lang-analogread>` on an unconnected pin. + +Conversely, it can occasionally be useful to use pseudorandom +sequences that repeat exactly. This can be accomplished by calling +``randomSeed()`` with a fixed number, before starting the random +sequence. + +Example +------- + +The following sketch initializes the random seed based on an :ref:`ADC +<adc>` reading of pin 0. If this pin is unconnected, the Sketch +should print different values to the :ref:`serial monitor +<ide-serial-monitor>` each time it is run:: + + long randNumber; + + void setup() { + pinMode(0, INPUT_ANALOG); + randomSeed(analogRead(0)); + } + + void loop() { + randNumber = random(300); + SerialUSB.println(randNumber); + + delay(50); + } + +See Also +-------- + +- :ref:`randomSeed() <lang-randomseed>` + +.. include:: /arduino-cc-attribution.txt |