int LDR = 0;       // select the input pin for the LDR
int lightOnPin = 13;   // select the pin for the LED
 
int val = 0;       // variable to store the value coming from the sensor
int turnOnValue = 1000;
void setup() {
  pinMode(LDR, INPUT);       // declare the LDR as an INPUT
  pinMode(lightOnPin, OUTPUT);  // declare the ledPin as an OUTPUT
  Serial.begin(9600);  
}
 
void loop() { 
  val = analogRead(LDR);       // read the value from the sensor
  Serial.print(val);
  if (val >= turnOnValue) {
    digitalWrite(lightOnPin, HIGH);  // turn the ledPin on
  } else {
    digitalWrite(lightOnPin, LOW);   // turn the ledPin off
  }
  delay(1000);
}