Arduino Programming Reference: Variables, Functions & Syntax

Classified in Computers

Written on June 16, 2026 in English with a size of 12.76 KB

Variables

Array

int myInts[6];
int myPins[] = {2, 4, 8, 3, 6};
int mySensVals[6] = {2, 4, -8, 3, 2};
char message[6] = "hello";

Bool

int LEDpin = 5;       // LED on pin 5
int switchPin = 13;   // momentary switch on 13, other side connected to ground
bool running = false;

void setup()
{
  pinMode(LEDpin, OUTPUT);
  pinMode(switchPin, INPUT);
  digitalWrite(switchPin, HIGH);      // turn on pullup resistor
}

void loop()
{
  if (digitalRead(switchPin) == LOW)
  {
    delay(100);                        // delay to debounce switch
    running = !running;                // toggle running variable
    digitalWrite(LEDpin, running);     // indicate via LED
  }
}

Char

char myChar = 'A';
char myChar = 65;      // both are equivalent

Double

Double precision floating point number. On the Uno and other ATMEGA-based boards, this occupies 4 bytes. That is, the double implementation is exactly the same as the float, with no gain in precision. On the Arduino Due, doubles have 8-byte (64-bit) precision.

Float

float var = val;

var - your float variable name
val - the value you assign to that variable

Int

int var = val;

var - your int variable name
val - the value you assign to that variable

String

char Str1[15];
char Str2[8] = {'a', 'r', 'd', 'u', 'i', 'n', 'o'};
char Str3[8] = {'a', 'r', 'd', 'u', 'i', 'n', 'o', '\0'};
char Str4[ ] = "arduino";
char Str5[8] = "arduino";
char Str6[15] = "arduino";

Void

void setup()
{
  // ...
}

void loop()
{
  // ...
}

Word

word w = 10000;

Functions

Digital I/O

Analog I/O

Zero, Due & MKR Family

Advanced I/O

Time

Math

Trigonometry

Characters

Random Numbers

Bits and Bytes

External Interrupts

Interrupts

Communication

USB

Structures

Constants

Conversion

Data Types

Variable Scope & Qualifiers

Utilities

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