Arduino programs can be divided in three main parts: structure, values (variables and constants), and functions.
Pointer Access Operators
Variable Scope & Qualifiers
Bits and Bytes
USB (32u4 based boards and Due only)
Looking for something else?
See the libraries page for interfacing with particular types of hardware. Try the list of community-contributed code. The Arduino language is based on C/C++. It links against AVR Libc and allows the use of any of its functions; see its user manual for details.
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.