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The random function generates pseudo-random numbers.
random(max)
random(min, max)
min - lower bound of the random value, inclusive (optional)
max - upper bound of the random value, exclusive
a random number between min and max-1 (long)
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.
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);
}
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