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.. _arduino-random:
random()
========
Description
-----------
The random function generates pseudo-random numbers.
Syntax
------
random(max)
random(min, max)
Parameters
----------
min - lower bound of the random value, inclusive *(optional)*
max - upper bound of the random value, exclusive
Returns
-------
a random number between min and max-1 (*long*)
Note:
-----
If it is important for a sequence of values generated by random()
to differ, on subsequent executions of a sketch, use randomSeed()
to initialize the random number generator with a fairly random
input, such as analogRead() on an unconnected pin.
Conversely, it can occasionally be useful to use pseudo-random
sequences that repeat exactly. This can be accomplished by calling
randomSeed() with a fixed number, before starting the random
sequence.
Example
-------
::
long randNumber;
void setup(){
Serial.begin(9600);
// if analog input pin 0 is unconnected, random analog
// noise will cause the call to randomSeed() to generate
// different seed numbers each time the sketch runs.
// randomSeed() will then shuffle the random function.
randomSeed(analogRead(0));
}
void loop() {
// print a random number from 0 to 299
randNumber = random(300);
Serial.println(randNumber);
// print a random number from 10 to 19
randNumber = random(10, 20);
Serial.println(randNumber);
delay(50);
}
See also
--------
- `randomSeed <http://arduino.cc/en/Reference/RandomSeed>`_\ ()
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