Arduino programs can be divided in three main parts: structure, values (variables and constants), and functions.
Pointer Access Operators
Variable Scope & Qualifiers
Zero, Due & MKR Family
Bits and Bytes
USB (32u4 based boards and Due/Zero 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.