const int buttonPin = 2;

int buttonState = 0;

int lastButtonState = 0;

void setup()
{
  Serial.begin(9600);
  pinMode(buttonPin, INPUT);
}

void loop()
{
  buttonState = digitalRead(buttonPin);

  if(buttonState == HIGH)
  {
     Serial.println("Button on");
  }else
  {
    Serial.println("Button off");
  }
  delay(100);
}