C# Intermediate: Classes, Interfaces and OOP from Udemy

Whether you want to use C# to build web apps, mobile apps, desktop apps or games, understanding C# classes, interfaces and principles of object-oriented programming is crucial.

This course is the second part of Mosh's best-selling C# series and is all about classes, interfaces and object-oriented programming. In essence, you'll learn:

How to work with classes, constructors, fields, properties, methods and indexers
How to use encapsulation to reduce the impact of change
How to improve the robustness of your code
How to re-use code using inheritance and composition
Why composition is better than inheritance
How to build extensible applications using polymorphism
How to develop loosely-coupled, extensible and testable applications using interfaces

Why would you want to take this course?

The answer is simple: quality of teaching.

Mosh is a passionate software engineer with over 13 years of experience developing applications in C#. He is the author of several best-selling C# courses on Udemy and knows how to lead you through a series of baby steps in a logical way.

So, from the very beginning to the very end, you'll be confident that you'll be in good hands and watching every minute of the course, unlike the reading many free tutorials and videos, does not waste your precious time.

Each section is equipped with a balanced mix of theory and practice. At the end of each section you'll get exercises to master the concepts you learn in that section.

And one last reason: all videos are produced with high quality video/audio, to provide you the best learning experience.

I owe a lot of it to you because your courses have been May God bless you and your efforts to create high quality courses. This has really changed my life from working as a security guard and doing websites for free, now I am a professional." -Danish Jafri

"Your courses have given me the confidence to get out of my dead end job and apply for a full time coding job. I am very happy to say that I just finished the job interview and they gave me the job. " -Dan Farnell

"Outstanding quality. I have come to learn that all Mosh's courses are top notch. This course is no different. The content is beautifully designed, well organized with great examples, and delivered in a clear and concise manner (with great video and audio quality). I also loved that this course includes exercises. Fantastic stuff. " -Roger Sæle

"Love it. This guy definitely knows what he's talking about. He strives to make his courses as comprehensive as possible and he teaches you several tricks along the way." -Jeb Watson

"As with all of his courses his passion and love for programming is infectious. He does a great job of intermixing theory with hard examples and cautions with practicality. If you learn better by watching and examples then reading and theory this is a must watch to move beyond the learning the syntax of c#." -Michael Paul

"Excellent course. All of Mosh's courses are very much worth taking if you really want to learn C# in a professional way. Not only does Mosh clearly describe the syntax of the language and explain the language concepts, but he also constantly emphasizes the importance of good programming practices" -Tony Zampini

NET Framework in 2002). Mosh is a full-time developer and what you are going to learn in this course is the result of his day-to-day work as a hardcore programmer along with years of studying,

100% MONEY- Take the course, go through the lectures, do the exercises, and if you're not happy, ask for a refund within 30 days. All your money back, no questions asked.

So do you want to take your C# skills to the next level? Then take this course now and get started.

What's inside

Learning objectives

Work with classes, constructors, fields, properties, methods and indexers
Use encapsulation to improve the robustness of the code and reduce the impact of change
Re-use code using inheritance and composition

Understand the problems with inheritance and how composition solves these problems
Change the behaviour of an application by extending its code, rather than changing it
Develop loosely-coupled, testable and extensible applications using interfaces

Work with classes, constructors, fields, properties, methods and indexers
Use encapsulation to improve the robustness of the code and reduce the impact of change
Re-use code using inheritance and composition
Understand the problems with inheritance and how composition solves these problems
Change the behaviour of an application by extending its code, rather than changing it
Develop loosely-coupled, testable and extensible applications using interfaces

Syllabus

About this Course

What You are Going to Learn

Who is Your Instructor

Source Code

Exercises

Asking Questions

Before You Get Started

Classes

What are classes and why we need them
What is the difference between a class and object
How to create classes, fields and methods
The var keyword
Static members

Constructors

How to quickly initialize objects without a constructor

What is method signature
What is method overloading
Method parameter modifiers: params, out and ref
Why ref is a smell in the design of C# and why you should avoid it.
Defensive programming and how it improves the robustness of your applications.

Two ways to initialize fields (directly and via constructor) and the pros and cons of each
The readonly modifier and how it improves the robustness of your code

Public and Private access modifiers
What is encapsulation?
Why we should declare fields as private and provider public accessors

What are properties and how to create them
A quick way to create a property

What are indexers, how they are useful and how to create them
The Dictionary type

Summary

Association between Classes

What is class coupling
What are tightly coupled and loosely coupled applications like
Three ways to reduce coupling

What is inheritance
An example of inheritance in a real-world scenario: building an application like Power Point
How to represent inheritance using UML
How to re-use code using inheritance

What is composition
An example of composition in a real-world scenario: DbMigrator and Logger
How to represent composition using UML
How to create a composition relationship between classes in C#

Why inheritance can easily be abused by amateur designers / developers
Problems with inheritance hierarchies
Why inheritance results in tight coupling between classes
How composition provides a more flexible and loosely coupled design

Inheritance - Second Pillar of OOP

Why access modifiers are important and how they help writing better code
Examples of public, private, protected, internal and protected internal
Why protected breaks encapsulation and it's better to be avoided

Rules about constructors in inheritance hierarchies
The base keyword and how we can use that to pass control to base class constructors

What is upcasting and down casting
Rules about casting an object to a base or derived class reference
The as and is keywords
StreamReader and ArrayList classes

What are value types and reference types
What is boxing and unboxing
Why boxing and unboxing comes with a performance penalty
Why generic lists are better to use than ArrayList

Polymorphism: Third Pillar of OOP

What is polymorphism and how we can achieve it by method overriding
The virtual and override keywords
How to get rid of long switch/case or if/else statements and re-write them in an object-oriented way with polymorphism

What are abstract classes and members
The abstract and override keywords
Rules about abstract classes and inheriting from them
When to use abstract classes

What are sealed classes and members
The sealed modifier

Interfaces

What is an Interface?

Introduction to Unit Testing with MS Tests framework
How interfaces improve the testability of your applications

I'll show you how we can change an application's behaviour without changing its code, simply by using interfaces as extensibility points. I'll also introduce you to the open-closed principle of object-oriented programming.

One of the common misconceptions about interfaces is that they are used for implementing multiple inheritance. This view is fundamentally wrong yet there are many books, videos and posts that make such claim. In this video I'll explain why interfaces got nothing to do with inheritance, single or multiple.

Interfaces provide polymorphic behaviour, which is extremely powerful. In this video, you'll see how we can use an interfaces in a polymorphic way to design a loosely-coupled and extensible application.

What's Next?

Final Words

My Other Courses

Get My Other Courses with a Discount

Bonus: Students' Code Reviews

StopWatch Exercise

Stack Exercise

Workflow Engine Exercise

Good to know

Know what's good

, what to watch for

, and possible dealbreakers

Develops key principles of object-oriented programming in C#, which are applicable to Java, JavaScript, Python, C++, and other languages

Taught by Mosh Hamedani, a recognized expert in software engineering and C# development

Examines core aspects of C#, including classes, interfaces, inheritance, polymorphism, encapsulation, and object-oriented design patterns

Provides practical exercises and assignments to reinforce concepts and allow learners to build projects

Covers essential concepts for building high-quality C# applications

Introduces advanced concepts such as polymorphism and interfaces for designing extensible and loosely coupled applications

Reviews summary

Useful oop intro

According to students, this course is a good starting point for learning about classes and object-oriented programming. Learners say that the exercises are helpful for practicing the material. However, some students say that you should practice by developing applications on your own.

Helpful for beginners

"The course is a good introduction to classes and object oriented programming which the exercises help to re-enforce."

Requires additional practice

"This course is a good starting point, but you should develop a lot of applications on it."

Activities

Be better prepared before your course. Deepen your understanding during and after it. Supplement your coursework and achieve mastery of the topics covered in C# Intermediate: Classes, Interfaces and OOP with these activities:

Compile a glossary of key terms

Show steps

Creating a glossary will help you memorize and understand the key terms used in this course.

Browse courses on Classes

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Review course materials and identify key terms.
Define each term in your own words.
Organize the terms alphabetically or by topic.

Seek out a mentor

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Finding a mentor can provide you with guidance and support throughout your learning journey.

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Identify individuals in the field you would like to learn from.
Attend industry events or meetups to connect with potential mentors.
Reach out to individuals and express your interest in mentorship.

Review basic programming concepts

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Revisiting basic programming concepts will provide a strong foundation for understanding the more advanced topics covered in this course.

Browse courses on Variables

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Review online tutorials or documentation on basic programming concepts.
Complete practice problems to reinforce your understanding.

Seven other activities

Expand to see all activities and additional details

Show all ten activities

Read Head First Java

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This book provides a comprehensive overview of Java and object-oriented programming concepts, which will complement the topics covered in this course.

View Head First Java: A Brain-Friendly Guide on Amazon

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Obtain a copy of the book.
Read one chapter per week.
Take notes and highlight important concepts.

Join a study group

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Collaborating with peers can provide a supportive environment for learning and help you stay motivated.

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Reach out to classmates and form a study group.
Set regular meeting times and discuss course materials.
Share notes and quiz each other.

Review tutorials on inheritance

Show steps

Watching tutorials can provide an alternative perspective on the concepts covered in this course and help you reinforce your understanding.

Browse courses on Inheritance

Show steps

Search for tutorials on inheritance.
Select a tutorial that aligns with your learning style.
Watch the tutorial and take notes.

Work through practice problems

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Practicing with sample problems will help you apply the concepts you learn in this course and identify areas where you need more support.

Browse courses on Classes

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Identify a problem set related to the topic you are studying.
Set a timer for 30 minutes.
Solve as many problems as you can within the time limit.
Review your answers and identify any errors.

Implement a class in your favorite programming language

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Building a class from scratch will help you solidify your understanding of their structure and functionality.

Browse courses on Classes

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Choose a class to implement.
Design the class interface, including properties, methods, and constructors.
Implement the class and test it thoroughly.

Build a simple application using object-oriented principles

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Applying your knowledge to build a real-world project will help you synthesize and retain the concepts covered in this course.

Browse courses on Classes

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Define the requirements and design for your application.
Implement the application using object-oriented principles.
Test and debug your application.

Volunteer to mentor students struggling with the course

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Mentoring others can not only strengthen your understanding of the course material but also positively impact your peers' learning experience.

Show steps

Reach out to your instructor or classmates to express your interest in mentoring.
Identify students who could benefit from your support.
Provide guidance and support on course-related topics.

Career center

Learners who complete C# Intermediate: Classes, Interfaces and OOP will develop knowledge and skills that may be useful to these careers:

Software Architect

Software Architects are responsible for designing, building, and maintaining the infrastructure of software systems. The course will help you develop the advanced skills needed for this role, such as designing extensible and loosely coupled applications using interfaces. You'll also learn how to use inheritance and composition to reuse code, and how to apply polymorphism to change the behavior of an application without changing its code.

See salaries and explore the career path for Software Architect

Software Developer

Software Developers design, develop, and test software systems. This course will help you build a strong foundation in object-oriented programming, which is essential for success in this role. You'll learn how to work with classes, constructors, fields, properties, methods, and indexers, and how to use encapsulation to improve the robustness of your code.

See salaries and explore the career path for Software Developer

Software Engineer

Software Engineers design, develop, and test software systems. This course will help you build a strong foundation in object-oriented programming, which is essential for success in this role. You'll learn how to work with classes, constructors, fields, properties, methods, and indexers, and how to use encapsulation to improve the robustness of your code.

See salaries and explore the career path for Software Engineer

Programmer

Programmers write and maintain code for software applications. This course will help you develop the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. You'll also learn how to use inheritance and composition to reuse code, and how to apply polymorphism to change the behavior of an application without changing its code.

See salaries and explore the career path for Programmer

Application Developer

Application Developers design, develop, and test software applications. This course will help you develop the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. You'll also learn how to use inheritance and composition to reuse code, and how to apply polymorphism to change the behavior of an application without changing its code.

See salaries and explore the career path for Application Developer

Computer Programmer

Computer Programmers write and maintain code for software applications. This course will help you develop the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. You'll also learn how to use inheritance and composition to reuse code, and how to apply polymorphism to change the behavior of an application without changing its code.

See salaries and explore the career path for Computer Programmer

Developer

Developers write and maintain code for software applications. This course will help you develop the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. You'll also learn how to use inheritance and composition to reuse code, and how to apply polymorphism to change the behavior of an application without changing its code.

See salaries and explore the career path for Developer

Web Developer

Web Developers design, develop, and maintain websites. This course will help you develop the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. You'll also learn how to use inheritance and composition to reuse code, and how to apply polymorphism to change the behavior of an application without changing its code.

See salaries and explore the career path for Web Developer

Systems Analyst

Systems Analysts design and implement computer systems. This course may help you develop some of the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. However, you will need additional training in systems analysis.

See salaries and explore the career path for Systems Analyst

Data Analyst

Data Analysts collect, analyze, and interpret data to help businesses make better decisions. This course may help you develop some of the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. However, you will need additional training in data analysis techniques.

See salaries and explore the career path for Data Analyst

Computer Systems Analyst

Computer Systems Analysts design, implement, and maintain computer systems. This course may help you develop some of the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. However, you will need additional training in computer systems analysis.

See salaries and explore the career path for Computer Systems Analyst

Database Administrator

Database Administrators maintain and administer databases. This course may help you develop some of the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. However, you will need additional training in database administration.

See salaries and explore the career path for Database Administrator

Technical Writer

Technical Writers create documentation for software and other technical products. This course may help you develop some of the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. However, you will need additional training in technical writing.

See salaries and explore the career path for Technical Writer

Information Security Analyst

Information Security Analysts protect computer systems from unauthorized access and use. This course may help you develop some of the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. However, you will need additional training in information security.

See salaries and explore the career path for Information Security Analyst

Project Manager

Project Managers plan and execute projects. This course may help you develop some of the skills you need to succeed in this role, such as how to work with classes, interfaces, and object-oriented programming principles. However, you will need additional training in project management.

See salaries and explore the career path for Project Manager