Object-Oriented Programming

Object

Everything around ourselves is an object in OOP. An object is the basic runtime entity in OOP which consists of data and functions. It stores data in variables.

Class

Generally, a class is a category/group which is used to identify some people or things in this world. A class provides the structure of an object and defines the prototype of the object.

Data Abstraction

It is data hiding. We can show only necessary information and can hide the unnecessary part. Abstraction is one of the key concepts of OOP languages.

Encapsulation

The wrapping of related data and functions (that operate on data) into a single unit (called a class) is known as encapsulation.

Polymorphism

The term polymorphism is formed by the combination of two Greek words: ‘poly’ (means many) and ‘morph’ (means form), i.e., the ability to take more than one form.

Advantages

Disadvantages

1. Single inheritance

In single inheritance, a class derives from one base class only. This means that there is only one subclass that is derived from one superclass.

2. Multiple inheritance

Multiple inheritance is a type of inheritance in which a class derives from more than one class. (Class C is a subclass that has Class A and Class B as its parents).

3. Multilevel inheritance

A derived class that is created from another derived class is called multi-level inheritance. This inheritance can have many levels as long as our implementation doesn’t go wayward.

4. Hybrid Inheritance

Hybrid inheritance is usually a combination of more than one type of inheritance (single, hierarchical, and multi-level).

5. Hierarchical inheritance

In hierarchical inheritance, more than one class inherits from a single base class. This gives it a structure of a hierarchy.

Object

Everything around ourselves is an object in OOP. An object is the basic runtime entity in OOP which consists of data and functions. It may represent a person, place, bank account, table of data, or any item that the program has to handle. It stores data in variables. Every object has two things: properties and behavior.

Example: Object – Student

Class

Generally, a class is a category/group which is used to identify some people or things in this world. A class provides the structure of an object and defines the prototype of the object. Every class has three important things: name, attributes/features, and operations/functions.

Example:

class Item {
private:
    int code;
    float price;
public:
    void get_data();
    void display_data();
};

Polymorphism

Polymorphism is a concept in object-oriented programming that allows objects of different classes to be treated as objects of a common superclass. It means “many forms” and it enables one interface to be used for different data types. There are two types of polymorphism:

Inheritance

Inheritance is a mechanism in OOP where one class (subclass or child class) acquires the attributes and methods of another class (superclass or parent class). This allows for code reuse and establishes a relationship between different classes. The subclass can add its own unique methods and properties in addition to the inherited ones. There are two main types of inheritance:

1. Single Inheritance

In single inheritance, a class derives from one base class only. This means that there is only one subclass that is derived from one superclass.

Fig: Single Inheritance

2. Multiple Inheritance

Multiple inheritance is a type of inheritance in which a class derives from more than one class.

Fig: Multiple Inheritance

3. Multilevel Inheritance

A derived class that is created from another derived class is called multilevel inheritance. This inheritance can have as many levels as long as our implementation doesn’t go wayward.

Fig: Multilevel Inheritance

4. Hybrid Inheritance

Hybrid inheritance is usually a combination of more than one type of inheritance (single, hierarchical, and multi-level).

Fig: Hybrid Inheritance

5. Hierarchical Inheritance

In hierarchical inheritance, more than one class inherits from a single base class as shown in the representation below. This gives it a structure of a hierarchy.

Fig: Hierarchical Inheritance