# random()

[Random Numbers]

## 描述

The random function generates pseudo-random numbers.

## 語法

```random(max)
random(min, max)```

## 參數

`min` – lower bound of the random value, inclusive (optional)
`max` – upper bound of the random value, exclusive

## 回傳

a random number between `min` 以及 `max-1` (long)

## 注意

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.

## 範例程式碼

```long randNumber;

void setup(){
Serial.begin(9600);

// noise will cause the call to randomSeed() to generate
// different seed numbers each time the sketch runs.
// randomSeed() will then shuffle the random function.
}

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);
}```

## 參考

### 語法參考主頁面

86Duino 參考的文本是根據 Creative Commons Attribution-ShareAlike 3.0 License，部分文本是從 the Arduino reference 修改的。 參考中的代碼示例已發佈到公共領域。

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