//Define LEDs
const int red = 12;
const int yellow = 11;
const int green = 10;
const int Button = 2;
// define time delays
int time_delay = 300;

int LEDchecker = 1;

// creating a string for the LEDs
const int size = 3;
byte LEDstring[size] = {red,yellow,green};

void setup() {
  // put your setup code here, to run once:
  pinMode(Button, INPUT);

  //must initialise pins as outputs and LEDs as off initally 
  initialise_pins();
  turn_off_pins();
}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(Button) == LOW){
   disco_lights();
   delay(time_delay); //having the delay outside of the function makes it easier to alter the delay
  }
}








// function to initialise pins
void initialise_pins(){
  for (int i = 0; i < size; i++){ //remember that indexing starts at 0
    pinMode(LEDstring[i], OUTPUT);
  } // to index a value in an array, you must use square brackets
    // the round brackets are for functions only
}
// turn off pins
void turn_off_pins(){
  for (int i = 0; i < size; i++){
     digitalWrite(LEDstring[i], LOW);
  }
}

// start blinking
void disco_lights(){
  if (LEDchecker == 1){
    digitalWrite(yellow, LOW);      
    digitalWrite(red, HIGH);
    digitalWrite(green, HIGH);
    LEDchecker = 2;
  }
  else{
    digitalWrite(red, LOW);
    digitalWrite(green, LOW);
    digitalWrite(yellow, HIGH);
    LEDchecker = 1;  
  }
}