// switches an LED on and off depending on light intensity 
const int ldrPin = A0; 
const int ledPin = 8; 

void setup() 
{
pinMode(ledPin, OUTPUT); 
}

void loop() {
int sensorValue = 100; 
if (sensorValue < 150) 
  digitalWrite(ledPin, HIGH);
else 
  digitalWrite(ledPin, LOW); 
}