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Learn C#

A free, interactive online C# course. You write C# on every lesson, with real C# code examples, AI hints when you're stuck, and a free certificate of completion when you finish.

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View syllabusC# playground

125,128+ codders enrolled

205 lessons186 challenges1,295 quiz questions

  • Beginner friendly
  • sparkles iconAI-assisted coding help
  • hint iconHands-on interactive lessons
  • volume On iconAudio narration on every lesson
  • quiz iconQuizzes to test your knowledge
  • certificate iconFree certificate of completion

Syllabus

3 sections3 projects205 lessons186 challenges1,295 quiz questions
  1. Section 1

    Fundamentals

    Start sectionStartExpandCollapse    Build a strong foundation with essential concepts and basic skills69 lessons63 challenges410 questions1 project

    Introduction

    4 lessons423

    Variables Part 1

    5 lessons539

    Variables Part 2

    5 lessons431

    Operators Part 1

    5 lessons438

    Operators Part 2

    5 lessons531

    Decision Making

    6 lessons638

    Basic IO

    6 lessons633

    Calculator App

    Project4 lessons1

    Loops

    8 lessons752

    Methods (Functions)

    6 lessons641

    Arrays Basics

    6 lessons629

    String Operations

    3 lessons324

    Iterating Over Collections

    3 lessons323

    Final Challenges

    3 lessons38
  2. Section 2

    Logic & Flow

    Start sectionStartExpandCollapse    Master advanced C# programming with a focus on data structures and flow control. Learn to work with complex arrays, collections, error handling, and time management.66 lessons77 challenges394 questions1 project

    Multi-dimensional Arrays

    7 lessons750

    Advanced Decision Making

    5 lessons932

    Loop Enhancements

    5 lessons632

    Flow Control Techniques

    5 lessons938

    Exception Handling

    8 lessons1160

    Null Handling

    5 lessons832

    Logical Operators Advanced

    4 lessons723

    Data Analysis System

    Project6 lessons1

    HashMap Part 1

    6 lessons536

    HashMap Part 2

    4 lessons415

    HashSet Part 1

    6 lessons537

    HashSet Part 2

    5 lessons539
  3. Section 3

    Object Oriented Programming

    Start sectionStartExpandCollapse    Discover how to organize code with classes, objects, and reusable structures70 lessons65 challenges491 questions1 project

    Fundamentals of OOP

    9 lessons972

    Properties & Static Members

    5 lessons545

    Class Architecture

    4 lessons427

    Inheritance

    6 lessons644

    Polymorphism & Interfaces

    6 lessons644

    Encapsulation

    5 lessons535

    Advanced Features

    5 lessons535

    Advanced OOP Concepts

    6 lessons653

    Variable Arguments

    4 lessons436

    Design Patterns Part 1

    5 lessons545

    Design Patterns Part 2

    6 lessons655

    Project: Library System

    Project6 lessons1

    Final Challenges

    3 lessons3

C# courses

Hands-on C# courses, free to start in your browser.

Interview PreparationData StructuresGraph Algorithms Courses

Beginner Challenges - Practice Basic Concepts

Popular

Put your beginner coding knowledge to test and try to solve this programming challenges, use any language you want, Happy Coding!

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Certificate on completion

  • 20
  • 20

Coding Problems

Popular

Put your programming problem solving skills to the test using the exercises with different difficulties in this course. Designed for coders with some prior knowledge of the basic syntax in any programming language.

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Certificate on completion

  • 32
  • 31

Stack - Data Structures Series #1

In this course, you will learn about the Stack data structure, create a Stack from zero using your preferred language, and practice coding challenges with it!

Data Structures
  • 13
  • 6
  • 1

Coding Problems: Volume 2

Put your programming problem solving skills to the test using the exercises with different difficulties in this course. Designed for coders with some prior knowledge of the basic syntax in any programming language. This course is an extension of the first Coding Problems

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Certificate on completion

  • 25
  • 24

Hash Tables - Data Structures Series #4

In this course, you will learn about the Hash Table data structure, create a Hash Table from zero using your preferred language, and practice coding challenges with it!

Data Structures
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Certificate on completion

  • 14
  • 12

Linked List - Data Structures Series #5

In this course, you will learn about the Linked List data structure, create a Linked List from zero using your preferred language, and practice coding challenges with it!

Data Structures
certificate icon

Certificate on completion

  • 14
  • 6
  • 1
See all 44 C# courses →
What you get
Everything you'll use to learn to code

Learn by Doing

Write real code, query databases, build websites, and master AI prompts. Our interactive lessons cover every skill modern developers need.

playground.js
Code Editor
1const greeting = "Hello, Coddy!"
2function sayHi(name) {
3    return greeting + " " + name
4}
5
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Test #1test Case Success icon
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Test #3test Case Failure icon
Input
"Alex"
Output
"Hello, Coddy! Alex"

Build Your Coding Streak

Stay consistent and watch your progress grow! Track your daily coding habit, protect your streak with freeze days, and earn rewards for showing up every day.

12 days streak

Return tomorrow to keep your streak!

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January 2026

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Double or Nothing

Day 5 of 7

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Streak Freeze

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Code Anywhere, Anytime

Take your coding journey on the go! No setup, no downloads - just open and start coding. Available on iOS, Android and Web with 4.9 star ratings.

Python
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Variables
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CONTINUE
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Journey
Goals
Leaderboard
Profile
4.9
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Rating

You're Not Alone in This

Compete on global leaderboards, invite friends to earn rewards, and celebrate each other's wins. Coding is better with friends!

Challenger League
Challenger LeagueTop 7 advance
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Alex7+ Days
2840
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Jordan7+ Days
2650
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Sam7+ Days
2420
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Casey
2180
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Morgan7+ Days
1950
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Every way to learn

Read, listen, test yourself, ask the AI, or look up anything you've already covered. Every lesson meets you where you are.

Intro to Variables
Audio

A variable is a named container that stores a value you can reference later in your program.

In Python, you create one by writing the name, an equals sign, then the value you want to store.

The value can change over time - reassigning the name simply points it to a new value.

1xSarah

Prove Your Skills

Earn certificates for every course you complete. Add them to your LinkedIn profile and resume to showcase your coding expertise to employers.

CoddyCertificate of Completion
This certifies thatJohn Doehas successfully completed
PythonPython Fundamentals
Verified
DateJan 2026
LinkedInAdd to LinkedIn

Why learn C# with Coddy

  • Write and run real C# code in your browser. No Visual Studio install, no .NET SDK setup. Each lesson compiles your C# program server-side and shows the output instantly.
  • Object-oriented C# the way it's used in production: classes, properties, inheritance, interfaces, generics, exception handling, LINQ. Code examples and exercises after every concept.
  • AI hints help you debug C# code and read compiler errors so the language feels approachable instead of intimidating, especially if you're new to OOP.
  • Free C# certificate of completion when you finish. Useful for game-dev (Unity), backend, and enterprise roles where C# fluency is a baseline expectation.

Frequently asked questions about learning C#

Is C# hard to learn?

C# is one of the more approachable strongly-typed languages. The syntax is consistent, the standard library is large and well-documented, and modern features like properties and pattern matching cut down on boilerplate. Most beginners get their first C# program running within the first hour and reach classes and inheritance within a week.

How long does it take to learn C#?

C# basics - syntax, methods, classes, objects - take two to four weeks of daily practice. Comfortable use of inheritance, interfaces, generics, and LINQ usually takes one to three months. Going deeper into ASP.NET, Unity game development, or enterprise patterns is a separate ramp.

What's the difference between C# and Java?

C# and Java are close cousins. Both are strongly-typed, class-based, garbage-collected. C# tends to adopt new features faster (properties, LINQ, async/await, pattern matching) and is heavily used for Unity game development and Windows tooling. Java leans more toward Android and large enterprise backends. The skills transfer in both directions.

Can I use C# for game development?

Yes. C# is the primary scripting language for Unity, one of the most popular game engines in the world. The OOP fundamentals you'll pick up here (classes, inheritance, interfaces) map directly to Unity's component model, so finishing the C# course gives you a real head start on Unity.

Can I learn C# online for free?

Yes. The interactive C# course is free - lessons, coding exercises, quizzes, and a certificate. The editor runs in your browser so you don't need to install Visual Studio, the .NET SDK, or any IDE to start writing C#.

Do I get a C# certificate after the course?

Yes. Finishing the C# course gives you a free certificate of completion you can add to your resume or share on LinkedIn - a verifiable signal alongside any Unity projects, .NET apps, or GitHub repos you've built.
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Learn C# with Coddy

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