• boolean operators
• Variable Declaration

A boolean holds one of two values, true or false. (Each boolean variable occupies one byte of memory.)

boolean

A boolean variable holds one of two values, true or false. (Each boolean variable occupies one byte of memory.)

boolean variables hold one of two values, true or false.

Even though it might be assumed that booleans should occupy only one bit of memory, they are treated by the compiler much the same as byte variables, and actually occupy one byte of memory.

boolean variables hold one of two values, true and false.

Even though it might be assumed that booleans should occupy only one bit of memory, they seem to be treated by the compiler much the same as byte variables, and actually occupy one byte of memory.

boolean variables hold one of two values, true and false.

boolean variables are hold one of two values, true and false.

boolean variables are one-bit variables that can only hold two values, true and false.

boolean running = false;

int switchPin = 13; // momentary switch on 13, other side connected to ground

int LEDpin = 5; // LED on pin 5 int switchPin = 13; // momentary switch on 13

  if (digitalRead(switchPin) == LOW)
  {  // switch is pressed - pullup keeps pin high normally
    delay(100);                        // delay to debounce switch
    running = !running;                // toggle running variable
    digitalWrite(LEDpin, running)      // indicate via LED
  }

Example

1. define LEDpin 5 // LED on pin 5
2. define switchPin 13 // momentary switch on 13

[@

void setup() {

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

void loop() {

  if (digitalRead(switchPin) == LOW){  // switch is pressed - pullup keeps pin high normally
  delay(100);                        // delay to debounce switch
  running = !running;                // toggle running variable
  digitalWrite(LEDpin, running)      // indicate via LED

running = -7; // negative numbers are non-zero (TRUE)

running = TRUE; // TRUE defined as 1

digitalWrite(switchPin, HIGH); // turn on pullup resistor

if (digitalRead(switchPin) == 0){ // switch is pressed - pullup keeps pin high normally

if (digitalRead(switchPin) == 0){ // switch is pressed - pullups keep pin high normally

delay(100); // delay to debounce switch

• constants

• boolean operators

boolean variables are one-bit variables that can only hold two values, 1 and 0. Note that the constants HIGH and LOW are also defined as 1 and 0, as are the variables TRUE and FALSE.

All of the following will set the variable running to a TRUE condition:

running = 35; // any non-zero number is TRUE running = -7; // negative numbers are non-zero running = HIGH; // HIGH is defined as 1 running = .125 // non-zero float defined as TRUE

Example

[@

1. define LEDpin 5 // LED on pin 5
2. define switchPin 13 // momentary switch on 13

[@ boolean running;

delay(100); // delay to debounce switch

// more statements

@]

See also

• Constants
• boolean operators?

@]

[@

• ]

boolean variables

boolean variables are one-bit variables that can only hold two values, 1 and 0. Note that the constants HIGH and LOW are also defined as 1 and 0, as are the variables TRUE and FALSE.

Example

1. define LEDpin 5 // LED on pin 5
2. define switchPin 13 // momentary switch on 13

[@ boolean running; boolean LEDon; int x;

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

void loop(){ if (digitalRead(switchPin) == 0){ // switch is pressed delay(50); // delay to debounce switch running = !running; // toggle running variable digitalWrite(LEDpin, running) // indicate via LED

}