Object-Oriented Programming (OOP)
Concept of OOP
- Problems are divided into objects.
- It is not possible to access data freely.
- Data hiding is possible.
- It uses a bottom-up programming approach.
- It is easy to add new data and functions.
- Data and functions are encapsulated into a single entity.
- In OOP, we created classes that have the power of reusability, i.e., these classes can be used by other programmers whenever they need them.
The main features of OOP are:
1. Object
In object-oriented programming (OOP), an object is an instance of a class, which is a blueprint or template for creating multiple objects with the same properties (attributes) and methods (functions). Each object is a separate and unique instance of a class, and it has its own data and behavior. Objects are used to represent real-world entities and their interactions.
For example, you can create a class called "Car," which has attributes such as make, model, year, and color and methods such as start, stop, and drive. Then you can create multiple objects of the class "Car," such as "myCar," "yourCar," and "hisCar," each having different attribute values but the same methods.
Objects in OOP interact with each other by sending messages, which invoke the methods of the object. This allows for encapsulation, where the internal state and behavior of an object are hidden from the outside world and can only be accessed through its methods.
2. Class
In object-oriented programming (OOP), a class is a blueprint or template for creating objects. It defines the properties (attributes) and methods (functions) that an object of that class will have. A class is a way to organize and structure code, and it is a blueprint for creating objects.
For example, you can create a class called "Car," which has attributes such as make, model, year, and color and methods such as start, stop, and drive. This class can be used as a template to create multiple "Car" objects, each with their own unique attribute values but the same methods.
A class defines the structure of an object, but it does not hold any specific data. When an object is created from a class, it is allocated memory and given its own set of attribute values.
A class can also inherit characteristics from another class through the mechanism of inheritance; this is a way to reuse code and create more specialized classes from existing ones.
In summary, a class in OOP is a blueprint for creating objects and provides a way to organize and structure code. It defines the properties and methods that the objects created from that class will have.
3. Inheritance
In object-oriented programming (OOP), inheritance is a mechanism that allows a new class to inherit the properties and methods of an existing class. It is one of the fundamental concepts of OOP and is used to create a hierarchy of classes, where a derived class inherits the properties and methods of a base class.
For example, you can create a class called "Vehicle" that has attributes such as the number of wheels and a method called "move." Then, you can create a class called "Car," which inherits from the "Vehicle" class and adds its own attributes such as make, model, and year, as well as methods such as start and stop. The "Car" class inherits all the attributes and methods of the "Vehicle" class and can also add new ones or override the ones inherited.
Inheritance allows for code reuse and promotes the DRY (don't repeat yourself) principle, where common functionality can be defined in a base class and inherited by derived classes, making the code more modular and easier to maintain.
Inheritance also allows for a more natural representation of real-world relationships, where a more specific class inherits the properties and methods of a more general class.
In summary, inheritance in OOP is a mechanism that allows a new class to inherit the properties and methods of an existing class; it allows for code reuse, promotes the DRY
Types of Inheritance
Some of the most common types of inheritance are:
a. Single Inheritance: A derived class inherits from a single base class. This is the most basic type of inheritance, where a derived class inherits properties and methods from a single base class.
In the given example, Class A is the parent class and Class B is the child class since Class B inherits the features and behavior of the parent class A .
b. Multiple Inheritance: A derived class inherits from multiple base classes. This allows a class to inherit properties and methods from multiple base classes, and it is supported in languages like C++ but not in others like Java or C#.
In given example, Class C inherits the properties and behavior of class B and class A at the same level. So, here A and Class B both are the parent classes for Class C.
d. Hierarchical Inheritance: A base class is inherited by multiple derived classes. This allows for a single base class to be inherited by multiple derived classes, promoting code reuse.
for example,
e. Hybrid Inheritance: A combination of multiple types of inheritance. This allows for the combination of different types of inheritance in a single program to take advantage of the strengths of each type.
Each type of inheritance has its own advantages and disadvantages, and it depends on the specific requirements of the problem domain to choose the appropriate type of inheritance.
4. Encapsulation
Encapsulation is a mechanism in object-oriented programming (OOP) that allows the internal state and behavior of an object to be hidden from the outside world. It is one of the fundamental concepts of OOP and is used to control access to an object's properties and methods.
Encapsulation is achieved by using access modifiers such as "public," "private," and "protected" to define the level of access to the properties and methods of a class. Public properties and methods can be accessed by any code, private properties and methods can only be accessed by the class itself, and protected properties and methods can be accessed by the class and its derived classes.
Encapsulation allows for the implementation of the "information hiding" principle, where the internal workings of an object are hidden from the outside world and can only be accessed through a well-defined interface. This allows for a greater degree of control over how an object's properties and methods are used, and it also makes the code more robust and less prone to errors.
Encapsulation also allows for the implementation of the "separation of concerns" principle, where the internal state and behavior of an object are separated from the external interface, making the code more modular and easier to maintain.
In summary, encapsulation is a mechanism in OOP that allows the internal state and behavior of an object to be hidden from the outside world. It is achieved by using access modifiers to define the level of access to the properties and methods of a class.
5. Polymorphism
Polymorphism is a mechanism in object-oriented programming (OOP) that allows objects of different classes to be used interchangeably. It is one of the fundamental concepts of OOP and is used to create a more flexible and extensible codebase.
There are two main types of polymorphism:
1.Compile-time polymorphism, also known as "overloading," allows for multiple methods with the same name but different parameter lists to be defined within the same class. This allows for method calls to be resolved at compile time based on the number, type, and order of the arguments passed.
2.Run-time polymorphism, also known as "overriding," allows a derived class to provide a different implementation of a method that is already defined in its base class. This allows for method calls to be resolved at runtime based on the actual type of the object at runtime.
Polymorphism allows for a more flexible and extensible codebase, where objects of different classes can be used interchangeably, and it promotes the "open/closed" principle, where a class should be open for extension but closed for modification.
In summary, polymorphism is a mechanism in OOP that allows objects of different classes to be used interchangeably; it is divided into compile-time polymorphism (overloading) and run-time polymorphism (overriding); it allows for a more flexible and extensible codebase; and it promotes the "open/closed" principle.
6. Abstraction
In summary, abstraction is a mechanism in OOP that allows the developer to focus on the essential features of an object while hiding its implementation details. It comes in the form of abstract classes and interfaces, allows for the separation of concerns, makes the code more modular and maintainable, and promotes the "program to an interface, not an implementation" principle.
Comparison between the Object-oriented Programming and Procedural Programming language:
Application of OOP
- Artificial Intelligence
- Management Information System
- Decision support system
- Object-oriented database
- Computer games
- Expert system
- Computer-based training and education
- Mobile application
- Security system
- Internet-based application
Conclusion
The focus of this discussion was on the concept of object-oriented programming language, its key features, and its various applications. One of the main benefits of OOP is its ability to encourage a "black box" mindset when designing and implementing software. The ultimate goal of this work was to design a programming language that fully integrates the principles of object-oriented programming, with a strong emphasis on the formal theory of classification.
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