// Constants
const int ldrPin = A0;     // Analog pin connected to the LDR
const int ledPin = 9;      // Digital pin connected to the LED
const int threshold = 500; // Threshold value for light

void setup() {
  // Initialize the LED pin as an output:
  pinMode(ledPin, OUTPUT);
  // Initialize serial communication for debugging:
  Serial.begin(9600);
}

void loop() {
  // Read the value from the LDR:
  int ldrValue = analogRead(ldrPin);
  // Print the LDR value to the serial monitor:
  Serial.println(ldrValue);
  // If the LDR value is less than the threshold, turn on the LED:
  if (ldrValue < threshold) {
    digitalWrite(ledPin, HIGH);
  } else {
    // Otherwise, turn off the LED:
    digitalWrite(ledPin, LOW);
  }
  // Wait for a short period before taking the next reading:
  delay(100);
}