The Arduino basically uses the industry-standard C++ language, implemented by the GNU g++ compiler.
For information on basic things like loops, strings, functions, data types, and so on try consulting one of the many online C++ references. Hint: Google "C++ tutorial".
Although the Arduino main page states that "the microcontroller on the board is programmed using the Arduino programming language (based on Wiring)" this should not be taken to mean that the Arduino is programmed in some sort of cut-down or "similar to C" variant.
The main sketch is C++, however the IDE does do a certain amount of pre-processing (in particular, generating function prototypes for you) before submitting the code to the main C++ compiler.
code arduino.txt (4.37 KB)