Driving LEDs

int timer = 1000;        
int ledPins[] = { 
   5,6,7,8, 9, 10,11, 12 };       // an array of pin numbers to which LEDs are attached
int pinCount = 8;           // the number of pins (i.e. the length of the array)

void setup() {
  // the array elements are numbered from 0 to (pinCount - 1).
  // use a for loop to initialize each pin as an output:
  for (int thisPin = 0; thisPin < pinCount; thisPin++)  {
    pinMode(ledPins[thisPin], OUTPUT);      
  }
}

void loop() {
  // loop from the lowest pin to the highest:
  for (int thisPin = 0; thisPin < pinCount; thisPin++) { 
    digitalWrite(ledPins[thisPin], HIGH);   
    delay(timer);                  
    digitalWrite(ledPins[thisPin], LOW);    

  }

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