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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[10]; 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.

See Also

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