This example is for Wiring version 0027+. If you have a previous version, use the examples included with your software. If you see any errors or have comments, please let us know.
Photoresistor by BARRAGAN
Reads values from a photoresistor connected to analog input pin 0 (or A0) and prints the result to the serial monitor The value read from the sensor is proportional to the amount of light that hits the sensor's surface.
int sensorValue;
void setup()
{
Serial.begin(9600); // starts the serial port at 9600
}
void loop()
{
sensorValue = analogRead(0); // read analog input pin 0
Serial.print(sensorValue, DEC); // prints the value read
Serial.print(" "); // prints a space between the numbers
delay(100); // wait 100ms for next reading
}