// C++ code
//
/*
  Button
  Turns on and off a light emitting diode(LED)
  connected to digital  pin 13, when pressing a
  pushbutton attached to pin 2.

   The circuit:
  * LED attached from pin 13 to ground
  * pushbutton attached to pin 2 from +5V
  * 10K resistor attached to pin 2 from ground
  * Note: on most Arduinos there is already an LED
  on the board  attached to pin 13.

  created 2005  by DojoDave <http://www.0j0.org>

  modified 30 Aug 2011  by Tom Igoe

  This example code is in the public domain.
  http://www.arduino.cc/en/Tutorial/Button
*/
//Arduino IDE中要用False,此处用false
bool buttonState = false;
bool lastButtonState = false;
bool lightState = false;

void setup()
{
  pinMode(2, INPUT);
  pinMode(LED_BUILTIN, OUTPUT);
}

void loop()
{
  // read the state of the pushbutton value
  buttonState = digitalRead(2);
  // check if pushbutton is pressed.  if it is, the
  // buttonState is HIGH
  if (buttonState != lastButtonState ) {
    // turn LED on
    lastButtonState = buttonState;
    if(buttonState){    //按下按键时开灯切换灯亮灭
    //if(!buttonState){  //释放按键时切换灯亮灭
      lightState = !lightState;
      digitalWrite(LED_BUILTIN, lightState);
    }
  } 
  delay(10); // Delay a little bit to improve simulation performance
}