Arduino distance sensor

distance.pde

int input = 8;
int redPin = 12;
int greenPin = 11;
int val = 0;

void setup() {
  pinMode(input, INPUT);
  pinMode(redPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  
  Serial.begin(9600);
}

void loop() {
  val = digitalRead(input);
  
  if (val == 0) {
    digitalWrite(greenPin, 1);
    digitalWrite(redPin, 0);
  }
  else {
    digitalWrite(greenPin, 0);
    digitalWrite(redPin, 1);
  }
  
  delay(100);
}