const int photoPin=A0;
int photoValue=0;
int lightVal=0;

void setup()
{
  // put your setup code here, to run once:

Serial.begin(9600);
pinMode(photoPin, INPUT);

}

void loop()
{
  // put your main code here, to run repeatedly:
photoValue=analogRead (photoPin);
lightVal=map (photoValue, 0, 907, 255, 0);
lightVal=constrain (lightVal, 0, 255);
Serial.print ("Photoresistor value =");
Serial.print(photoValue);
Serial.print ("lightVal =");
Serial.println(lightVal);
delay (100);
}