Analog Input -- 3.3V vs. 5V?

Hello!

I am creating a machine that has a SPDT switch on it connecting the input to either the 5V and 3.3V switch depending on the toggle, as I don't have many pins left for my project's inputs. I was wondering if a single analog input was capable of differentiating between the two, and if so, how I would accomplish this. I do have an external pull-up resistor connecting the input to my ground so I do not get any "funky" values.

Thanks in advance!

The analog input can very easily distinguish between 3.3 and 5V.

Try the analogRead examples that come with the Arduino IDE.