Getting Started with Arduino

VARIABLES

Variables are named areas of the Arduino's memory where you can store data that you can use and manipulate in your sketch. As the name suggests, they can be changed as many times as you like.

Because Arduino is a very simple processor, when you declare a variable you have to specify its type. This means telling the processor the size of the value you want to store.

Here are the datatypes that are available:

boolean

Can have one of two values: true or false.

char

Holds a single character, such as A. Like any computer, Arduino stores it as a number, even though you see text. When chars are used to store numbers, they can hold values from –128 to 127.

Note

There are two major sets of characters available on computer systems: ASCII and UNICODE. ASCII is a set of 127 characters that was used for, among other things, transmitting text between serial terminals and time-shared computer systems such as mainframes and minicomputers. UNICODE is a much larger set of values used by modern computer operating systems to represent characters in a wide range of languages. ASCII is still useful for exchanging short bits of information in languages such as Italian or English that use Latin characters, Arabic numerals, and common typewriter symbols for punctuation and the like.

byte

Holds a number between 0 and 255. As with chars, bytes use only one byte of memory.

int

Uses 2 bytes of memory to represent a number between –32,768 and 32,767; it's the most common data type used in Arduino.

unsigned int ...