int ledPins[] = {2, 3, 4, 5, 6, 7, 8, 9}; // Defines an array to store the pin numbers of the 8 LEDs.
// An array is like a list variable that can store multiple numbers.
// Arrays are referenced or "indexed" with a number in the brackets [ ]. See the examples in
// the pinMode() functions below.
void setup()
{
  // setup all 8 pins as OUTPUT - notice that the list is "indexed" with a base of 0.
  pinMode(ledPins[0], OUTPUT); // ledPins[0] = 2
  pinMode(ledPins[1], OUTPUT); // ledPins[1] = 3
  pinMode(ledPins[2], OUTPUT); // ledPins[2] = 4
  pinMode(ledPins[3], OUTPUT); // ledPins[3] = 5
  pinMode(ledPins[4], OUTPUT); // ledPins[4] = 6
  pinMode(ledPins[5], OUTPUT); // ledPins[5] = 7
  pinMode(ledPins[6], OUTPUT); // ledPins[6] = 8
  pinMode(ledPins[7], OUTPUT); // ledPins[7] = 9
}
void loop() {
  // This loop() calls functions that we've written further below.
  // We've disabled some of these by commenting them out (putting
  // "//" in front of them). To try different LED displays, remove
  // the "//" in front of the ones you'd like to run, and add "//"
  // in front of those you don't to comment out (and disable) those
  // lines.
  // oneAfterAnother(); // Light up all the LEDs in turn
  // oneOnAtATime();
  // pingPong();
  // marquee();
  // Turn on one LED at a time
  // Same as oneOnAtATime() but change direction once LED reaches edge
  // Chase lights like you see on theater signs
  // Blink LEDs randomly
  randomLED();
}
/******************************************************************
  oneAfterAnother()

  This function turns all the LEDs on, pauses, and then turns all
  the LEDS off. The function takes advantage of for() loops and
  the array to do this with minimal typing.
  /*****************************************************************/
void oneAfterAnother()
{
  int index;
  int delayTime = 100; // milliseconds to pause between LEDs
  // make this smaller for faster switching
  // Turn all the LEDs on:
  for (index = 0; index <= 7; index = ++index) // step through index from 0 to 7
  {
    digitalWrite(ledPins[index], HIGH);
    delay(delayTime);
  }
  // Turn all the LEDs off:
  for (index = 7; index >= 0; index = --index) // step through index from 7 to 0
  {
    digitalWrite(ledPins[index], LOW);
    delay(delayTime);
  }
}
/*****************************************************************
  oneOnAtATime()

  This function will step through the LEDs, lighting only one at
  a time. It turns each LED ON and then OFF before going to the
  next LED.
  /****************************************************************/
void oneOnAtATime()
{
  int index;
  int delayTime = 100; // milliseconds to pause between LEDs
  // make this smaller for faster switching
  for (index = 0; index <= 7; index = ++index) // step through the LEDs, from 0 to 7
  {
    digitalWrite(ledPins[index], HIGH); // turn LED on
    delay(delayTime);
    // pause to slow down
    digitalWrite(ledPins[index], LOW); // turn LED off
  }
}
/*****************************************************************
  pingPong()

  This function will step through the LEDs, lighting one at at
  time in both directions. There is no delay between the LED off
  and turning on the next LED. This creates a smooth pattern for
  the LED pattern.
  /****************************************************************/
void pingPong()
{
  int index;
  int delayTime = 100; // milliseconds to pause between LEDs
  for (index = 0; index <= 7; index = ++index) // step through the LEDs, from 0 to 7
  {
    digitalWrite(ledPins[index], HIGH); // turn LED on
    delay(delayTime);
    // pause to slow down
    digitalWrite(ledPins[index], LOW); // turn LED off
  }
  for (index = 7; index >= 0; index = --index) // step through the LEDs, from 7 to 0
  {
    digitalWrite(ledPins[index], HIGH); // turn LED on
    delay(delayTime);
    // pause to slow down
    digitalWrite(ledPins[index], LOW); // turn LED off
  }
}
/*****************************************************************
  marquee()

  This function will mimic "chase lights" like those around
  theater signs.
  /****************************************************************/
void marquee()
{
  int index;
  int delayTime = 200; // milliseconds to pause between LEDs
  // Step through the first four LEDs
  // (We'll light up one in the lower 4 and one in the upper 4)
  for (index = 0; index <= 3; index++) // Step from 0 to 3
  {
    digitalWrite(ledPins[index], HIGH); // Turn a LED on
    digitalWrite(ledPins[index + 4], HIGH); // Skip four, and turn that LED on
    delay(delayTime);
    // Pause to slow down the sequence
    digitalWrite(ledPins[index], LOW); // Turn the LED off
    digitalWrite(ledPins[index + 4], LOW); // Skip four, and turn that LED off
  }
}
/*****************************************************************
  randomLED()

  This function will turn on random LEDs. Can you modify it so it
  also lights them for random times?
  /****************************************************************/
void randomLED()
{
  int index;
  int delayTime;
  index = random(8); // pick a random number between 0 and 7
  delayTime = 100;
  digitalWrite(ledPins[index], HIGH); // turn LED on
  delay(delayTime);
  // pause to slow down
  digitalWrite(ledPins[index], LOW); // turn LED off
}