int LDRInput=13; //Set Analog Input A0 for LDR.
int LED=2;
void setup()
{
Serial.begin(9600);
pinMode(LDRInput,INPUT);
pinMode(LED,OUTPUT);
}
void loop()
{
int value=digitalRead(LDRInput); //Reads the Value of LDR(light).
Serial.println("LDR value is :");
Serial.println(LDRInput); //Prints the value of LDR to Serial Monitor.
if(value)
 {
 digitalWrite(LED,HIGH); //The LED turns ON in Dark.
 }
 else
 {
 digitalWrite(LED,LOW); //The LED turns OFF in Light.
 }
}