#define LDR_PIN 2
#define LED_PIN 4
void setup() {
  // put your setup code here, to run once:
  pinMode(LDR_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedlY;
  if(digitalRead(LDR_PIN))
  digitalWrite(LED_PIN,HIGH);
  else digitalWrite(LED_PIN,LOW);

}