int sensorPin = A0;
int ledPin = 9;

void setup()
{
  Serial.begin(9600);
  // We'll set up the LED pin to be an output.
  pinMode(ledPin, OUTPUT);
}

void loop()
{
  int lightLevel = analogRead(sensorPin); //Reading the light intensity from the analog input

  lightLevel = map(lightLevel, 0, 1023, 0, 255); //Adjusting the output digital port to the input reading from the analog input
  lightLevel = constrain(lightLevel, 0, 255);

  Serial.print("\n lightLevel =");
  Serial.print(lightLevel);
if (lightLevel >= 50)
{
  analogWrite(ledPin, HIGH); //Writing an analog value to the LED
  delay(100);
}else{
  analogWrite(ledPin, LOW); //Writing an analog value to the LED
  delay(100);
}
  // The above statement will brighten the LED along with the
  // light level. To do the opposite, replace "lightLevel" in the
  // above analogWrite() statement with "255-lightLevel".
  // Now you've created a night-light!
}