50 things to know about C # Microsoft's OOP language running .NET, Unity games,

50 things to know about C #

C # (read C Sharp) is Microsoft's OOP language, running .NET, Unity Games, Windows Desktop, and Enterprise Backend.

Part 1 Basics and History

1. Created year 2000

Anders Hejlsberg, creator of TypeScript and Delphi, designed C # up at Microsoft

2.C # is not C + +

Despite the C-like name, C # runs on .NET runtime, not compiled into a straight machine code, closer to Java.

3. NET Framework vs .NET Modern

.NET Framework Only Windows (Legacy) .NET 6/7/8 to Cross-platform, Open Source Runs on Linux, macOS, Windows

4.CLR (Common Language Runtime)

.NET's Virtual Machine runs Java's JVM-like Intermediate Language (IL).

5. Open Source since 2014

Microsoft opens C # and .NET as open source. It currently fully supports Linux / Mac.

Part 2 Variables and Data Types

6. Built-in Types

int, double, string, bool, char covers the general task. Double has suffix m for decimal precision.

7. Var Keyword

Var name = "John" Compiler can guess the type. No need to write the type straight, shorter.

8.Nullable Types

int? age = null. Get null. C # 8 + has nullable reference types. Prevent NullReferenceException

9. Value vs Reference Types

Value (int, struct, enum) Keep straight value Reference (class, string, array) Store reference

10. Constants

Const (compile-time) readonly (runtime) is used for non-changing values.

Part 3 OOP

11. Classes

Dog class has Property, Constructor, Method. Create an instance with new Dog () Basic OOP.

12. Properties

Name {get; set;} is more convenient than Java auto-implemented getter / setter with expression body = >

13. Inheritance

Dog class: Inherited Animal. Use virtual + override instead of Java's final / sealed.

14. Interfaces

IComparable < T > beginning with I shows the capabilities of Java-like classes.

15. Abstract Classes and sealed

abstract = must override sealed = do not inherit opposite

Part 4 Collections

16.List, Dictionary, HashSet

List < T > Like ArrayList Dictionary < K, V > Like HashMap HashSet < T > Like Java Set

17. LINQ

Language Integrated Query Where, OrderBy, Select Write functional query more powerful than Java's Stream API.

18.Query Syntax (LINQ)

From u in users where... Orderby... Select SQL embedded-like format in the language.

19.IEnumerable vs IQueryable

IEnumerable in-memory IQueryable defer execution translate to SQL in the Entity Framework

20. Tuples

Var (name, age) = GetPerson () returns multiple values, convenient deconstruction

Part 5 Generics

21. Generic Classes

Box < T > can get multiple types, similar to Java Generics, but runtime really knows type, not erase.

22. Generic Constraints

Where T: IComparable < T > Limited Acceptable Type Insert Multiple Conditions

Part 6 Async / Await

23. Async / await

C # is the first language to do standard async / await. Write asynchronous code to look like synchronous.

24. Task vs Task < T >

Task Not Return Task Value < T > Return ValueTask Value optimized for sync path

25. Cancellation Token

Cancel task Send token to each method. Consider canceling.

Part 7 Modern Features

26. Records (C # 9 +)

Person record (string name, int Age) immutable, value equality, deconstruction.

27. Pattern Matching

Switch expression supports pattern check type, deconstruct, condition combined in one place

28. Top-level Statements (C # 9 +)

You don't have to write the Main method in Program.cs. Write the code down. It fits a small project.

29. String Interpolation

$"Hello {name}" Insert variable in raw string literal text (C # 11 +) for multi-line

30. Nullable Reference Types (C # 8 +)

Open# nullableEnabled compilers will warn when using null with reference type accidentally.

Part 8 Exception Handling

31. Try-catch-finally.

Cover code that may error catch by exception type. Finally do every time, whether error or not.

32. Using Statements

Using var file =... Auto Dispose Ending scope good resource leak protection

Part 9 Delegates and Events

33. Delegates

Function pointer of C # defines the signature of the function and then assigns the function.

34. Func, Action, Predicate

Func < T, TResult > return Action < T > No return Predicate < T > return bool can be used instead of custom delegate

35. Events

Observer pattern is built-in subscribe with + = published when event is born

Part 10 Frameworks and Ecosystem

36. ASP.NET Core.

Framework Create Web API, Microservices Fast, Cross-platform Minimal API Write very short endpoint

37. Entity Framework Core

The ORM of .NET code-first migrations, LINQ to SQL, manages the Database without writing SQL straight.

38. Blazor.

Create a Web UI with C # instead of JavaScript. Can do WebAssembly or Server-Side

39. MAUI (Multi-platform App UI)

Framework creates Desktop + Mobile (iOS, Android, Windows, Mac) from a single codebase.

40. Unity.

Game Engine uses C # as its primary language. Most Mobile, Console, VR / AR app games use Unity.

Part 11. NET Ecosystem

41. NuGet

.NET's package manager is like npm, pip install library through dotnet add package.

42. Dotnet CLI.

The dotnet new, build, run, test command is used to create and manage projects through the line command.

43. Visual Studio vs Rider vs VS Code

Visual Studio Super Full (Windows / Mac) Rider of JetBrains Premium VS Code + C # DevKit Free Lightweight

Part 12 Best Practices

44. Naming Conventions

Class / Method / Property PascalCase Variable / Parameter camelCase Interface Initial I (IUserSeries)

45. Async whole chain

Do not call .Result or .Wait () on Task. Deadlock. Use await throughout the chain.

46. Disposed Pattern

Class using unmanaged resources (file, socket, DB) must implement IDisposable and call Dispose ().

47. SOLID + DI

C # has Dependency Injection built-in in ASP.NET Core. Use DI Container instead of new objects themselves.

Part 13 is amazing.

48. Stack Overflow uses C #

The Stack Overflow web that every developer uses is built with ASP.NET (C #).

49. Microsoft Office Add-ins

Create add-in for Excel, Word, PowerPoint with VSTO (C #)

500.C # is Java for Microsoft.

Designed to race Java directly, but many say C # is much more modern than Java (Records, Pattern Matching, async / await before).

Summary C # is a modern and powerful language. Fits Enterprise Backend, Game Dev (Unity), Desktop and Cross-platform Apps. With .NET being a cross-platform, C # has become a good choice, not losing to Java.

# CSharp # DotNet # Coding # Programming# Backend