Configures the specified pin to behave either as an input or an output. See the description of digital pins for details on the functionality of the pins.
As of Arduino 1.0.1, it is possible to enable the internal pullup resistors with the mode INPUT_PULLUP. Additionally, the INPUT mode explicitly disables the internal pullups.
pin: the number of the pin whose mode you wish to set
The analog input pins can be used as digital pins, referred to as A0, A1, etc.
Corrections, suggestions, and new documentation should be posted to the Forum.
The text of the Arduino reference is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.