Exploring Photo Resistors Activity

/*
*Divya Inaganti
*June 14, 2017
*How to use a photo resistor activity
*/
const int photoPin= A0 ;
int photoValue = 0;
int lightVal= 0;
void setup()
{
  Serial.begin (9600);
  pinMode(photoPin, INPUT);
 }
void loop()
{
  photoValue= analogRead (photoPin);
  lightVal= map(photoValue, 0, 1020, 255, 0);
  lightVal= constrain(lightVal, 0, 255);
  Serial.print ("Photoresistor value = ");
  Serial.print(photoValue);
  Serial.print ("lightVal = ");
  Serial.println(lightVal);
  delay(100);
}