Arduino - RandomSeed

Arduino

Reference Language | Libraries | Comparison | Changes

## randomSeed(seed)

#### Description

randomSeed() initializes the pseudo-random number generator, causing it to start at an arbitrary point in its random sequence. This sequence, while very long, and random, is always the same.

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.

#### Parameters

long, int - pass a number to generate the seed.

#### Returns

no returns

#### Example

    long randNumber;

    void setup(){
      Serial.begin(9600);
      randomSeed(analogRead(0));
    }

    void loop(){
      randNumber = random(300);
      Serial.println(randNumber);

      delay(50);
    }

#### See also

- random

Reference Home

Corrections, suggestions, and new documentation should be posted to the Forum.

The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.

### Share

### This link has expired.
Please re-subscribe to our Newsletters.

### Subscribe to our Newsletters

Email

Please enter a valid email to subscribe

Arduino Newsletter
Arduino Store Newsletter

### Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy

###### Newsletter

- ©2015 Arduino
- Copyright Notice
- Contact us
- About us
- Careers