C# Object Oriented Programming for Beginners

C# Programming Guide

This programming tutorial discusses Object Oriented Programming (OOP), its features and benefits, and how programmers can work with it in C#.

What is Object Oriented Programming in C#?

Object-Oriented Programming (OOP) is a way of writing code that uses objects to model the real world. In object-oriented programming, the building blocks of a program are called objects (which can be anything from a car to a book).

Each object comprises a set of properties and methods. A class, meanwhile, is a template for creating objects (i.e., classes are used to create an object based on its blueprint). Classes contain properties and methods that define your objects’ behavior in certain situations or scenarios in your program.

OOP was developed to overcome the drawbacks of older programming paradigms, such as procedural programming. In the procedural programming paradigm, you write code as a list of instructions that are executed sequentially.

This can often lead to issues such as duplicate code, where the same code is written in multiple places, or spaghetti code, where code is so interconnected that it is difficult to understand or change.

OOP aims to solve these problems by encapsulating data and code into individual objects. This allows for more modular and maintainable code. It also enables developers to create relationships between different objects, making it easier to model real-world scenarios.

What are The Benefits of OOP?

There are many benefits to using Object-Oriented Programming, or OOP, in your applications. OOP can help make code more manageable and organized, as well as making it easier to reuse code. Additionally, OOP can make it easier to create software that is more reliable and easier to maintain.

How to Create an Object from a Class

A class is a template or blueprint for creating objects. Objects are instances of classes. You can create an object from a class and access its attributes and methods by using dot notation like this:

Car car = new Car();

Principles of Object-Oriented Programming

The idea of an object in OOP is that it is a self-contained entity with its own behavior. Any object comprises its own state, behaviour, and attributes. For example, you can have an object of type Employee that will have properties like Name, Basic, and Salary. You can also perform operations on an Employee instance using methods such as AddEmployee(), GetEmployeeSalary(), etc. This brings us to the first principle of OOP: encapsulation.

Encapsulation means hiding the implementation details from other programs or users of your program so that they do not need to know how things work internally in order to use them effectively (or even at all). This allows you to change how things are implemented without having any effect on their external behavior or interface.

Another principle of OOP is Polymorphism. Polymorphism is the ability to take on different forms, and it is one of the most powerful features of OOP. Polymorphism allows you to use the same method name with different parameters, which makes your code more flexible and reusable.

Polymorphism allows one object to take on multiple forms. This means that an object can be treated as if it were of different types, depending on context. Polymorphism allows programmers to build objects and then use those objects in several ways. For example, consider a simple class named Shape.

A developer could create a class named Square and another named Circle, where both inherit from a common base class named Shape. In both these classes – Square and Circle – you can have a method named CalculateArea(). Then you can create an instance of a Square or Circle using a reference of type Shape and then invoke the CalculateArea() method.

The code example below illustrates how these classes can be created in C#:

abstract class Shape
{
    public virtual int CalculateArea()
    {
        return -1;
    }
}
class Square : Shape
{
    public override int CalculateArea()
    {
        return 0;
    }
}
class Circle : Square
{
    public override int CalculateArea()
    {
        return 0;
    }
}

You can now use the following code to create an instance of the Circle class and then invoke the CalculateArea() method:

Shape s = new Circle(); //Creates an instance of the Circle class
s.CalculateArea(); //Invokes the CalculateArea() of the Circle class

Abstraction is another OOP principle. Abstraction is a process in which the details of how something is implemented are hidden from the external world. Essentially, the idea is quite simple: abstraction allows you to concentrate on what it does, rather than on how it accomplishes that task. Abstraction provides a simple way to organize and manage complexity.

Inheritance is also an object-oriented principle. Inheritance is a mechanism for creating new classes from existing ones. The original class is called the “base” or “parent” class, while the derived or “child” class is the one that inherits from it. Inheritance creates a relationship between two classes that allows you to reuse existing code in your application.

Inheritance creates a relationship between two classes that allows you to reuse existing code in your new program, making it simpler and more efficient to develop software. And, by using inheritance, you can extend existing classes to create new ones without having to write all the code from scratch.

The final principle of object-oriented programming is Composition. Composition is a principle in which a class contains one or more classes or their instances, (i.e., it is composed of another class or instances of other classes). Many prefer composition over inheritance while designing classes since inheritance can be detrimental to performance as the inheritance hierarchies grow. Moreover, composition allows you to change dependencies if needed.

Final Thoughts on Object Oriented Programming in C#

Object Oriented Programming (OOP) is a great way to organize and reuse code. By creating classes, you can group together related data and methods. You can take advantage of OOP in C# to build applications that are flexible because the code is reusable code and maintainable.

Read more C# programming tutorials and coding tips.

Joydip Kanjilal
Joydip Kanjilal
A Microsoft Most Valuable Professional in ASP.NET, Speaker, and Author of several books and articles. More than 25 years of experience in IT with more than 18 years in Microsoft .NET and its related technologies. He was selected as a Community Credit Winner at http://www.community-credit.com several times. He has authored 8 books and more than 500 articles in some of the most reputed sites worldwide including MSDN, Info World, CodeMag, Tech Beacon, Tech Target, Developer, CodeGuru, and more.

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