Binary Arithmetic and Port Manipulation

//boolean ledState[8] = {0, 0, 0, 0, 0, 0, 0, 0};
byte ledState = 0;

void setup() {
  //  for (int i = 0; i < 8; i++) {
  //    pinMode(i, OUTPUT);
  //  }
  DDRD = B11111111;
}

void loop() {
  for (int i = 0; i < 8; i++) {
    //digitalWrite(i,HIGH);
    //ledState[i] = HIGH;
    bitSet(ledState, i);
    adjustLedState();
    delay(100);

  }
  for (int i = 0; i < 8; i++) {
    //digitalWrite(i,LOW);
    //ledState[i] = LOW;
    bitClear(ledState, i);
    adjustLedState();
    delay(100);
  }
}

void adjustLedState() {
  //  for (int i = 0; i < 8; i++) {
  //    //digitalWrite(i,ledState[1] );
  //    digitalWrite(i, bitRead(ledState, i));
  //  }
  PORTD  = ledState;
}