Hello Arduinos,
Here is wrong typing I guess, pls check this link, http://arduino.cc/en/Tutorial/WhileLoop and you will see like this ==> (const int sensorPin = A2; // pin that the sensor is attached to). I think it should be A0 instead of A2 by the figure. 
Could be.
I would have used byte also instead of int.
Only admins can fix that, we moderators don't have privileges.
The description and sample code are consistent with each other and both show A2 being used, the picture showing the connection to A0 is inconsistent.