Random()

Random()

• Description

Use function random() will generate pseudo random numbers.

• Syntax

random(max) random(min, max)

• Parameter

min - The minimum value of a random number, which is included in the random number. （optional） max - The maximum value of a random number, which is not included in the random number.

• Return

A random number between min and max-1（the data type is long ）.

• Note

If you need a truly random number to be generated in a random() sequence, when its subsequence is being executed , use function randomSeed() to preset an absolute random input, for example, the returned value of function analogRead() in a disconnected pin.

On contrary, sometimes, accurate repeat of the pseudo random bumber is also useful. This can be completed before the start of a random sequence, through calling a randomSeed() with a fixed value.

• Example

long randNumber;
 
void setup(){
  Serial.begin(9600);
 	
//If the analog input pin 0 is disconnected, it will imitate noise randomly. 
//It will call randomSeed() to generate when each run of the code. 
//Different seed values. 
//RandomSeed() will randomly disturb function random.
  randomSeed(analogRead(0));
}
 
void loop() {
//Print a random number between 0 to 299.
  randNumber = random(300);
  Serial.println(randNumber);  
 
//Print a random number between 10 to 19. 
  randNumber = random(10, 20);
  Serial.println(randNumber);
 
  delay(50);
}

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