int ledPins[] = {2,3,4,5,6,7,8,};
void setup() {
  int index;
  
  for(index = 0; index <= 7; index++)
  {
    pinMode(ledPins[index],OUTPUT);
    // ledPins[index] is replaced by the value in the array.
    // For example, ledPins[0] is 2
  }

  

}

void loop() {
  int index;
  int delayTime = 100; // milliseconds to pause between LEDs
                       // make this smaller for faster switching
  
  // step through the LEDs, from 0 to 7
  
  for(index = 0; index <= 7; index++)
  {
    digitalWrite(ledPins[index], HIGH);  // turn LED on
    delay(delayTime);                    // pause to slow down
    digitalWrite(ledPins[index], LOW);   // turn LED off
  }      
 

}