Object-Oriented Programming (OOP) is a programming paradigm that uses objects and classes for organizing code. It is based on several key concepts that help structure and design software in a more modular and organized way. The main OOP concepts are:
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Objects: Objects are instances of classes. They represent real-world entities, combining both data (attributes) and behaviours (methods) into a single unit. For example, you can have an "Employee" class with objects representing individual employees.
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Classes: A class is a blueprint or template for creating objects. It defines the structure (attributes) and behaviour (methods) that its objects will have. Classes serve as a blueprint for creating multiple objects with the same characteristics.
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Encapsulation: Encapsulation is the concept of bundling data (attributes) and the methods (functions) that operate on that data into a single unit (object or class). This helps in hiding the internal details and providing a clear interface for interacting with objects. Access modifiers like public, private, and protected control the visibility of attributes and methods.
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Inheritance: Inheritance is a mechanism that allows a new class (subclass or derived class) to inherit properties and behaviours (attributes and methods) from an existing class (base class or superclass). It promotes code reuse and hierarchy in object structures.
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Polymorphism: Polymorphism means "many shapes" and refers to the ability of objects of different classes to be treated as objects of a common superclass. It allows you to define methods in a base class and override them in derived classes. Polymorphism also includes concepts like method overloading and method overriding.
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Abstraction: Abstraction is the process of simplifying complex reality by modelling classes based on essential properties and behaviours. It involves defining the essential characteristics of an object while ignoring the non-essential details. Abstract classes and interfaces are used to achieve abstraction in many programming languages.
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Association: Association represents a relationship between two or more classes where objects of one class are related to objects of another class. It can be one-to-one, one-to-many, or many-to-many. For example, in a library system, there is an association between the "Library" class and the "Book" class.
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Composition: Composition is a stronger form of association where one class contains objects of another class as part of its own structure. This is often used to model "has-a" relationships. For example, a "Car" class may have a "Wheel" class as one of its components.
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Aggregation: Aggregation is a special form of association where one class represents a whole and another class represents a part. It is a weaker relationship than composition. For instance, a "University" class can be associated with many "Student" classes.
These OOP concepts provide a powerful way to design and structure software systems by promoting modularity, reusability, and maintainability. Different programming languages may implement these concepts in slightly different ways, but the core principles remain consistent across most object-oriented programming languages.