C++ Arduino - 随机函数不起作用

Question

Hi C++ Devs and StackOverflow users!

The code following is what I did, but some reason, random function doesn't work, or output for a result always the same value which is '1', did I do anything wrong? How should I fix this issue?

  void setup()           
  {
  int randNumber;
  int i;

  randNumber = random(2);
  Serial.println(randNumber);
  pinMode(PIEZO, OUTPUT);
  delay(3000);

  if (randNumber == 0)
  {
    for (i = 0; i < 105; i++)                                       
    {
      tone(PIEZO, notes[i], time[i]);                                
      delay(time[i]);
    }
  }
  else if (randNumber == 1)                                     
    for (i = 0; i < 116; i++)                                       
    {
      tone(PIEZO, Snowman_Notes[i], Snowman_Rhythm[i]);                                  
      delay(Snowman_Rhythm[i]);
    }
}
void loop()                                                      
{
}

Answer 1

You need to seed random first. Use randomSeed(seed) .

Before using any PRNG (pseudo random number generator), you have to seed the generator. The seed should be different every time otherwise you'll get the same sequence over and over. That is, if you call randomSeed(2); and then call random() , you'll get the same numbers in the same order every time. The pattern of numbers are the same for a given seed. As mentioned in the comments, only seed ONCE per program

So, you'll want to seed the PRNG with a different number every time. Taken from the website , you can just used randomSeed( analogRead(pinNum) ); , where pinNum should be an unconnected pin.