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What is C# and .NET?

C# course · Beginner · Lesson 1/116

Learn that C# is a powerful, modern language and how the .NET runtime works.

What is C#?

C# is a powerful, type-safe programming language developed by Microsoft. With version 12 it is a modern, multi-purpose language.

C# programs run on the .NET platform. .NET provides an environment that compiles and runs your code.

You can build websites, desktop apps, games (Unity) and cloud services with C#.

What can you build with C#?

C# is a multi-purpose language. The most common use cases are:

  • Web: fast and secure sites with ASP.NET Core
  • Desktop: window apps with Windows Forms or WPF
  • Games: 2D and 3D games with the Unity engine
  • Cloud: microservices on Azure

This flexibility makes C# popular worldwide.

Test yourself

  1. Where do C# programs run?

    • On the Java virtual machine
    • On the .NET platform
    • In the browser
    • In the operating system kernel
    Show answer

    On the .NET platform — Correct! C# code runs on the .NET platform.

  2. Match the concepts

    C#
    Language
    .NET
    Platform
    CLR
    Runtime
    IL
    Intermediate code

  3. Which can NOT be done with C#?

    • Build a website
    • Make a game (Unity)
    • Write a browser extension
    • Build a desktop app
    Show answer

    Write a browser extension — Correct! Browser extensions are written in JavaScript, not C#.

  4. Where does C# run?

    C# runs on the ____ platform.
    Show answer 
    C# runs on the .NET platform.

All lessons in Beginner

1 C# basics

  1. What is C# and .NET?
  2. Your first program
  3. Console.WriteLine
  4. Comments
  5. Compile and run
  6. Summary - C# basics

2 Variables

  1. Declaring variables
  2. The var keyword
  3. Constants
  4. Type inference
  5. Variable scope
  6. Summary - Variables

3 Data types

  1. Integer types
  2. Floating-point types
  3. Char and bool
  4. String basics
  5. Value and reference types
  6. Summary - Data types

4 Project: Calculator

  1. Project design
  2. Add and subtract
  3. Multiply and divide
  4. Error handling
  5. Putting it together

5 Operators

  1. Arithmetic operators
  2. Assignment operators
  3. Comparison operators
  4. Logical operators
  5. Bitwise operators
  6. Summary - Operators

6 String basics

  1. Declaring strings
  2. String interpolation
  3. String concatenation
  4. String.Format
  5. Verbatim strings
  6. Summary - String basics

7 Conditionals

  1. The if statement
  2. else and else if
  3. The switch statement
  4. Pattern matching
  5. The ternary operator
  6. Summary - Conditionals

8 Loops

  1. The for loop
  2. The while loop
  3. The do-while loop
  4. The foreach loop
  5. break and continue
  6. Summary - Loops

9 Project: Shopping cart

  1. Cart design
  2. Adding products
  3. Calculating totals
  4. Updating quantity
  5. Putting it together

10 Arrays

  1. Declaring arrays
  2. Array access
  3. Array length
  4. Multidimensional arrays
  5. Jagged arrays
  6. Summary - Arrays

11 Array methods

  1. Array.Sort
  2. Array.Reverse
  3. Array.IndexOf
  4. Array.Copy
  5. Array.Find and FindAll
  6. Summary - Array methods

12 Collections

  1. List<T> basics
  2. List<T> methods
  3. Dictionary<K,V>
  4. Dictionary access
  5. HashSet<T>
  6. Summary - Collections

13 Methods

  1. Defining methods
  2. Return values
  3. void methods
  4. Method overloading
  5. Local functions
  6. Summary - Methods

14 Method parameters

  1. Parameterized methods
  2. Default parameters
  3. The params keyword
  4. ref parameters
  5. out parameters
  6. Summary - Method parameters

15 Project: To-do CLI

  1. Task model
  2. Adding tasks
  3. Listing tasks
  4. Completing tasks
  5. Putting it together

16 Advanced string methods

  1. Substring
  2. IndexOf and LastIndexOf
  3. Split and Join
  4. Trim and Pad
  5. Replace
  6. Summary - Advanced strings

17 Console I/O

  1. Console.ReadLine
  2. Console.ReadKey
  3. int.Parse and TryParse
  4. double.Parse
  5. Console formatting
  6. Summary - Console I/O

18 Enums

  1. Defining enums
  2. Enum values
  3. Enum casting
  4. Enum.Parse
  5. Flags attribute
  6. Summary - Enums

19 Exception basics

  1. try/catch
  2. finally block
  3. throw
  4. The Exception class
  5. Custom exceptions
  6. Summary - Exception basics

20 Beginner final

  1. Project design
  2. Data model
  3. Business logic
  4. Error handling
  5. Putting it together