random()

1long randNumber;
2
3    void setup() {
4      Serial.begin(9600);
5
6      // if analog input pin 0 is unconnected, random analog
7      // noise will cause the call to randomSeed() to generate
8      // different seed numbers each time the sketch runs.
9      // randomSeed() will then shuffle the random function.
10      randomSeed(analogRead(0));
11    }
12
13    void loop() {
14      // print a random number from 0 to 299
15      randNumber = random(300);
16      Serial.println(randNumber);
17
18      // print a random number from 10 to 19
19      randNumber = random(10, 20);
20      Serial.println(randNumber);
21
22      delay(50);
23    }