/* Using a slide switch to turn the LED ON and OFF
   https://github.com/ostad-ai/Arduino-Tutorial
*/
//The common contact of the slide switch is connected
//to the GROUNG by sliding the slider to the left, 
//so the pin value at switch_pin becomes LOW. 
//In contrast, by sliding the slider of switch to the right,
// it is disconnected. Since we define switch_pin as INPUT_PULLUP,
// it is read as HIGH if the pin is disconnected.
const int LED_pin=13, switch_pin=3;
void setup() {
  // put your setup code here, to run once:
  pinMode(LED_pin, OUTPUT);
  pinMode(switch_pin, INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly:
  int switch_state=digitalRead(switch_pin);
  digitalWrite(LED_pin, switch_state);  
}