# %

## Description

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.

## Syntax

remainder = dividend % divisor;

## Parameter Values

• 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() { values[i] = analogRead(0); i = (i + 1) % 10; // remainder operator rolls over variable }

※ NOTES AND WARNINGS:

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.