Arduino data types and constants.

Constants

Floating Point Constants
Integer Constants
HIGH | LOW
INPUT | OUTPUT | INPUT_PULLUP
LED_BUILTIN
true | false

Conversion

byte()
char()
float()
int()
long()
word()

Data Types

String()
array
bool
boolean
byte
char
double
float
int
long
short
size_t
string
unsigned char
unsigned int
unsigned long
void
word

Variable Scope & Qualifiers

const
scope
static
volatile

Utilities

PROGMEM
sizeof()