Arduino Cookbook, 2nd Edition

Chapter 3. Using Mathematical Operators

3.0. Introduction

Almost every sketch uses mathematical operators to manipulate the value of variables. This chapter provides a brief overview of the most common mathematical operators. As the preceding chapter is, this summary is primarily for nonprogrammers or programmers who are not familiar with C or C++. For more details, see one of the C reference books mentioned in the Preface.

3.1. Adding, Subtracting, Multiplying, and Dividing

Problem

You want to perform simple math on values in your sketch. You want to control the order in which the operations are performed and you may need to handle different variable types.

Solution

Use the following code:

int myValue;
myValue = 1 + 2;  // addition
myValue = 3 - 2;  // subtraction
myValue = 3 * 2;  // multiplication
myValue = 3 / 2;  // division (the result is 1)

Discussion

Addition, subtraction, and multiplication for integers work much as you expect.

Note

Make sure your result will not exceed the maximum size of the destination variable. See Recipe 2.2.

Integer division truncates the fractional remainder in the division example shown in this recipe’s Solution; myValue will equal 1 after the division (see Recipe 2.3 if your application requires fractional results):

int value =   1 + 2 * 3 + 4;

Compound statements, such as the preceding statement, may appear ambiguous, but the precedence (order) of every operator is well defined. Multiplication and division have a higher precedence than addition and subtraction, so ...