Toggling Button

const int  buttonPin = 2;    // the pin that the pushbutton is attached to
const int ledPin = 13;       // the pin that the LED is attached to

// Variables will change:
int buttonState = 0;         // current state of the button
int lastButtonState = 0;     // previous state of the button
int ledState = false;

void setup() {
  // initialize the button pin as a input:
  pinMode(buttonPin, INPUT_PULLUP);
  // initialize the LED as an output:
  pinMode(ledPin, OUTPUT);
}


void loop() {
  // read the pushbutton input pin:
  buttonState = digitalRead(buttonPin);

  // compare the buttonState to its previous state
  if (buttonState != lastButtonState) {
    // change detected, if button is down (inverted since pullup),
    // invert led state
    if (buttonState == LOW)
      ledState = !ledState;
    digitalWrite(ledPin, ledState);
     // Delay a little bit to avoid bouncing
    delay(50);
  }

  // save the current state as the last state,
  //for next time through the loop
  lastButtonState = buttonState;
}