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<p class='vspace'></p><h2>random()</h2>
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<p>The random function generates pseudo-random numbers.
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<p class='vspace'></p><h4>Syntax</h4>
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<p>random(max)<br />random(min, max)
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<p class='vspace'></p><h4>Parameters</h4>
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<p>min - lower bound of the random value, inclusive <em>(optional)</em>
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<p class='vspace'></p><p>max - upper bound of the random value, exclusive
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<p class='vspace'></p><h4>Returns</h4>
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<p>a random number between min and max-1 (<em>long</em>)
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<p class='vspace'></p><h4>Note: </h4>
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<p>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.
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<p class='vspace'></p><p>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.
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<p class='vspace'></p><h4>Example</h4>
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// if analog input pin 0 is unconnected, random analog
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// noise will cause the call to randomSeed() to generate
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// different seed numbers each time the sketch runs.
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// randomSeed() will then shuffle the random function.
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randomSeed(analogRead(0));
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// print a random number from 0 to 299
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randNumber = random(300);
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Serial.println(randNumber);
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// print a random number from 10 to 19
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randNumber = random(10, 20);
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Serial.println(randNumber);
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<p class='vspace'></p><h4>See also</h4>
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<ul><li><a class='wikilink' href='RandomSeed.html'>randomSeed</a>()
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