//https://docs.arduino.cc/built-in-examples/control-structures/Arrays/

//https://docs.arduino.cc/built-in-examples/control-structures/Arrays/


int timer = 100;
int ledPins[] = {
  2,3,4,5,6,7
};
int pinCount = 6;

void setup() {
  // the array of elements are numbered from 0 to (pinCount - 1)
  for (int thisPin = 0; thisPin < pinCount; thisPin++)
  pinMode(ledPins[thisPin], OUTPUT);
  }

void loop() {
  // loop from low->highest pin
  for(int thisPin = 0; thisPin < pinCount; thisPin++){
    //turn pin on:
    digitalWrite(ledPins[thisPin], HIGH);
    delay(timer);

    //turn pin off
    digitalWrite(ledPins[thisPin], LOW);
  }
  //loop from highest->lowest pin:
  for(int thisPin = pinCount -1; thisPin >= 0; thisPin --){
  //turn pin on:
  digitalWrite(ledPins[thisPin], HIGH);
  delay(timer);
  //turn pin off:
  digitalWrite(ledPins[thisPin], LOW);
}
}