Programming Glossary

This programming glossary defines some of the most commonly used programming terms throughout this book. It doesn’t include operators and symbols.


The #define operator defines a value that persists throughout an entire application. For instance:

#define NUMBER 4

Now the constant NUMBER will represent the value 4 throughout the application.


The #ifdef operator checks whether something has been defined using the #define keyword. It must be followed by #endif.


The #ifndef operator checks whether something has not been defined using the #define keyword. It must be followed by #endif.


This is short for ampere and is a electrical measurement of how much electrical current is flowing in a circuit. It is equal to the voltage divided by the resistance.

analog pin

On the Arduino, the analog pins enable reading of voltage. The voltage on the pin is interpreted as an integer value in the range of 0 to 1,023.


An array is a collection of variables that are accessed with an index number. An array is declared with a length or with initializers that determine the length. The following code declares an array of six elements with the first element at arr[0] and the last at arr[5]:

int arr[6];

Processing arrays are created like so:

int arr = new int[6];

In C++, declaring the array initializes each element in the array when the object is created only if the array is declared in the class:

class myClass {int arr[6]; // will be created when an instance of // myClass ...

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