LED_Button_Registers.ino

const int LED = 2;
const int button = 5;


void setup() {
  // put your setup code here, to run once:
  //pinMode(button, INPUT_PULLUP);
  //pinMode(LED, OUTPUT);
  DDRD = B00000100;
  PORTD = B00100000;
}

void loop() {

  //int reading = digitalRead(button);
  //int reading = (PIND & (B00100000)) >> 5;
  int reading = (PIND & (1 << 5)) >> 5;
  
  if (reading){
    //digitalWrite(LED, LOW);
    //PORTD = PORTD & B11111011
    PORTD = PORTD & ~(1 << 2);
  }
  else {
    //digitalWrite(LED, HIGH);
    //PORTD = PORTD | (B00000100);
    PORTD = PORTD | (1<<2);
  }
}