# %

[Arithmetic Operators]

## 描述

Remainder operation calculates the remainder when one integer is divided by another. It is useful for keeping a variable within a particular range (e.g. the size of an array). The `%` (percent) symbol is used to carry out remainder operation.

## 語法

`remainder = dividend % divisor;`

## 參數

`remainder`: variable. Allowed data types: `int``float``double`.
`dividend`: variable or constant. Allowed data types: `int`.
`divisor`non zero variable or constant. Allowed data types: `int`.

## Example Code

```int x = 0;
x = 7 % 5;  // x now contains 2
x = 9 % 5;  // x now contains 4
x = 5 % 5;  // x now contains 0
x = 4 % 5;  // x now contains 4
x = -4 % 5; // x now contains -4
x = 4 % -5; // x now contains 4```
```/* update one value in an array each time through a loop */

int values;
int i = 0;

void setup() {}

void loop() {
i = (i + 1) % 10; // remainder operator rolls over variable
}```

## Tips

1. The remainder operator does not work on floats.
2. If the first operand is negative, the result is negative (or zero). Therefore, the result of `x % 10` will not always be between 0 and 9 if `X` can be negative.

### 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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