Variables and Data Types

Create variable

To create a variable:

variableType variableName;

For example:

int a;

To create a variable and initialize it:

variableType variableName = initialValue;

For example:

int a = 2;

Assign value to a variable

If you have a variable declared before, you can assign some value to it:

For example:

int a;  // declared previously
a = 2;

Or change the value:

int a = 3;  // initalized previously
a = 2;

Variable types

• char : signed 1-byte character value
• byte : unsigned 8-bit integer
• int : signed 16-bit (on ATMEGA based boards) or 32-bit (on Arduino Due) integer
• unsigned int : unsigned 16-bit (on ATMEGA based boards) or 32-bit (on Arduino Due) integer
• long : signed 32-bit integer
• unsigned long : unsigned 32-bit integer
• float : 4-byte floating point number
• double : 4-byte (on ATMEGA based boards) or 8-byte (on Arduino Due) floating point number

Examples:

char a = 'A';
char a = 65;

byte b = B10010;

int c = 2;

unsigned int d = 3;

long e = 186000L;

unsigned long f = millis(); // as an example

float g = 1.117;

double h = 1.117;