Page 66 - Viva ICSE Computer Studies 8 : E-book

Class

A class is a collection of similar objects. For example, fruits is a class.

A class is a blueprint of an object. It defi nes the data and function column to a particular object.
So, let’s say you want to use a person in your program. You want to describe the person and
have the person do something. A class called ‘person’ would provide a blueprint for what a
person looks like and what a person can do. To actually use a person in your program, you
need to create an object. You use the person class to create an object of the type ‘person.’
A class consist of two aspects: variables and functions. A variable forms the state of an object
and a function uses these variables to perform various operations. Once a class is defi ned,
we can create many objects belonging to that same class but all the objects should share a
common state and behavior. All objects belonging to a particular class are called instances of
that class.

Features of Object–Oriented Programming

Object-oriented programming (OOP) is the latest approach in programming. It attempts to
eliminate most of the drawbacks of procedure-oriented programming by incorporating new
concepts. It is a new way of organising programs which is not dependent upon any particular
language. Let’s look at some of the features of object-oriented programming.

Abstraction

Abstraction means to ignore the unnecessary details of an object and access all the essential
details. Let’s understand the concept with an example. When you do online shopping you
simply order the item and pay for it. So, here the user is concerned about the payment and
shopping. He never comes to know the background process. Classes use this concept and

represent essential properties of the objects.

Encapsulation

The wrapping of data and functions in an object or class is known as encapsulation. It prevents
the data from unauthorised access and from getting misused. Encapsulation ensures that the
user cannot access the data without proper authorisation. Let’s understand the concept with
an example.
Suppose you go to an automatic cola vending machine and request for a cola. The machine

processes your request and gives you cola.
Here, the automatic cola vending machine is a class. It contains both data, i.e., cola can, and
operations, i.e., service mechanism and they are wrapped/integrated under a single unit, cola
vending machine. This is called encapsulation.

Inheritance

Inheritance is one such concept where the properties of one class can be inherited by the
other. A class which inherits the properties is known as child class whereas a class whose

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