Member variable

In object-oriented programming

Object-oriented programming

Object-oriented programming is a programming paradigm using "objects" – data structures consisting of data fields and methods together with their interactions – to design applications and computer programs. Programming techniques may include features such as data abstraction,...

, a member variable (sometimes called a member field

Field (computer science)

In computer science, data that has several parts can be divided into fields. Relational databases arrange data as sets of database records, also called rows. Each record consists of several fields; the fields of all records form the columns....

) is a variable

Variable (programming)

In computer programming, a variable is a symbolic name given to some known or unknown quantity or information, for the purpose of allowing the name to be used independently of the information it represents...

 that is associated with a specific class

Class (computer science)

In object-oriented programming, a class is a construct that is used as a blueprint to create instances of itself – referred to as class instances, class objects, instance objects or simply objects. A class defines constituent members which enable these class instances to have state and behavior...

, and accessible for all its methods

Method (computer science)

In object-oriented programming, a method is a subroutine associated with a class. Methods define the behavior to be exhibited by instances of the associated class at program run time...

. If there is only one copy of the variable shared with all instances of the class, it is called a class variable

Class variable

In object-oriented programming with classes, a class variable is a variable defined in a class of which a single copy exists, regardless of how many instances of the class exist.A class variable is the opposite of an instance variable...

 or static member variable. If each instance of the class has its own copy of the variable, the variable is called an instance variable

Instance variable

In object-oriented programming with classes, an instance variable is a variable defined in a class , for which each object of the class has a separate copy. They live in memory for the life of the object....

.