#define DO_PIN 2  // Arduino's pin connected to DO pin of the ldr module

void setup() {
  
  Serial.begin(9600);
  // initialize the Arduino's pin as an input
  pinMode(DO_PIN, INPUT);
}

void loop() {
  int lightState = digitalRead(DO_PIN);

  if (lightState == HIGH)
    Serial.println("The light is NOT present");
  else
    Serial.println("The light is present");
}