The C# Player's Guide. 5 Ed

Table of Contents....10

Acknowledgments....20

Introduction....22

The Great Game of Programming....22

Book Features....23

Speedruns....23

Challenges and Boss Battles....24

Knowledge Checks....25

Experience Points and Levels....25

Narratives and the Plot....25

Side Quests....26

Glossary....26

The Website....26

Discord....26

I Want Your Feedback....27

An Overview....27

Part 1: The Basics....28

1 The C# Programming Language....30

What is C#?....30

What is .NET?....31

2 Getting an IDE....32

A Comparison of IDEs....32

Visual Studio....33

Visual Studio Code....33

Visual Studio for Mac....33

JetBrains Rider....33

Other IDEs....33

Online Editors....34

No IDE....34

Installing Visual Studio....34

3 Hello World: Your First Program....36

Creating a New Project....36

A Brief Tour of Visual Studio....38

Compiling and Running Your Program....39

Syntax and Structure....40

Strings and Literals....41

Identifiers....41

Hierarchical Organization....41

Classes and Methods....42

Namespaces....42

The Base Class Library....43

Program and Main....43

Statements....44

Whitespace....44

Beyond Hello World....45

Multiple Statements....45

Expressions....45

Variables....46

Reading Text from the Console....47

Compiler Errors, Debuggers, and Configurations....48

Compiler Errors and Warnings....48

Debugging....48

Build Configurations....48

4 Comments....50

How to Make Good Comments....51

5 Variables....53

What is a Variable?....53

Creating and Using Variables in C#....54

Integers....55

Reading from a Variable Does Not Change It....56

Clever Variable Tricks....56

Variable Names....57

6 The C# Type System....59

Representing Data in Binary....59

Integer Types....60

Declaring and Using Variables with Integer Types....61

The Digit Separator....62

Choosing Between the Integer Types....62

Binary and Hexadecimal Literals....63

Text: Characters and Strings....63

Floating-Point Types....64

Scientific Notation....66

The bool Type....66

Type Inference....67

The Convert Class and the Parse Methods....68

Parse Methods....69

7 Math....71

Operations and Operators....71

Addition, Subtraction, Multiplication, and Division....72

Compound Expressions and Order of Operations....73

Special Number Values....75

Integer Division vs. Floating-Point Division....75

Division by Zero....76

More Operators....76

Unary + and - Operators....76

The Remainder Operator....76

Updating Variables....77

Increment and Decrement Operators....78

Prefix and Postfix Increment and Decrement Operators....78

Working with Different Types and Casting....79

Overflow and Roundoff Error....81

The Math and MathF Classes....82

π and e....82

Powers and Square Roots....82

Absolute Value....82

Trigonometric Functions....83

Min, Max, and Clamp....83

More....83

The MathF Class....83

8 Console 2.0....84

The Console Class....84

The Write Method....84

The ReadKey Method....85

Changing Colors....85

The Clear Method....85

Changing the Window Title....86

The Beep Method....86

Sharpening Your String Skills....86

Escape Sequences....86

String Interpolation....87

Alignment....87

Formatting....88

9 Decision Making....90

The if Statement....90

Block Statements....91

Blocks, Variables, and Scope....92

The else Statement....94

else if Statements....94

Relational Operators: ==, !=, <, >, <=, >=....95

Using bool in Decision Making....96

Logical Operators....97

Nesting if Statements....98

The Conditional Operator....98

10 Switches....100

Switch Statements....101

Multiple Cases for the Same Arm....102

Switch Expressions....102

Switches as a Basis for Pattern Matching....103

11 Looping....105

The while Loop....105

The do/while Loop....107

Variables Declared in Block Statements and Loops....107

The for Loop....107

break Out of Loops and continue to the Next Pass....108

Nesting Loops....109

12 Arrays....111

Creating Arrays....112

Getting and Setting Values in Arrays....112

Default Values....113

Crossing Array Bounds....113

Indexing from the End....114

Ranges....114

Other Ways to Create Arrays....114

Some Examples with Arrays....115

The foreach Loop....116

Multi-Dimensional Arrays....116

13 Methods....118

Defining a Method....118

Local Functions....119

Calling a Method....120

Methods Get Their Own Variables....121

Passing Data to a Method....122

Multiple Parameters....123

Copied Values in Method Calls....123

Returning a Value from a Method....124

Returning Early....125

Multiple Return Values?....125

Method Overloading....125

Simple Methods with Expressions....126

XML Documentation Comments....127

The Basics of Recursion....128

14 Memory Management....130

Memory and Memory Management....131

The Stack....131

Parameters....134

Return Values....136

Fixed-Size Stack Frames....136

The Heap....136

The Heap as a Graph of Objects....138

Value Types and Reference Types....139

Value Semantics and Reference Semantics....142

Cleaning Up Heap Memory....143

Automatic Memory Management....143

Part 2: Object-Oriented Programming....148

15 Object-Oriented Concepts....150

Object-Oriented Concepts....150

16 Enumerations....153

Enumeration Basics....154

Defining an Enumeration....154

Using an Enumeration....155

Revisiting ConsoleColor....156

Underlying Types....157

17 Tuples....158

The Basics of Tuples....159

Tuple Element Names....160

Tuples and Methods....160

More Tuple Examples....161

Deconstructing Tuples....162

Ignoring Elements with Discards....163

Tuples and Equality....163

18 Classes....165

Defining a New Class....166

Instances of Classes....168

Constructors....169

Default Constructors and Default Field Values....170

Constructors with Parameters....170

Multiple Constructors....171

Initializing Fields Inline....171

Name Hiding and the this Keyword....172

Calling Other Constructors with this....174

Leaving Off the Class Name....174

Object-Oriented Design....174

19 Information Hiding....176

The public and private Accessibility Modifiers....177

The Default Accessibility Level is private....180

When to Use private and public....180

Accessibility Levels as Guidelines, Not Laws....180

Abstraction....180

Type Accessibility Levels and the internal Modifier....181

20 Properties....184

The Basics of Properties....184

Auto-Implemented Properties....187

Immutable Fields and Properties....188

Object Initializer Syntax and Init Properties....189

Anonymous Types....190

21 Static....191

Static Members....191

Static Fields....191

Global State....192

Static Properties....192

Static Methods....193

Static Constructors....193

Static Classes....194

22 Null References....195

Null or Not?....196

Disabling Nullable Type Warnings....196

Checking for Null....197

Null-Conditional Operators: ?. and ?[]....197

The Null Coalescing Operator: ??....198

The Null-Forgiving Operator: !....198

23 Object-Oriented Design....199

Requirements....200

Designing the Software....201

Noun Extraction....201

UML....202

CRC Cards....202

Evaluating a Design....205

Creating Code....206

How to Collaborate....208

Creating New Objects....208

Constructor Parameters....208

Method Parameters....208

Asking Another Object....209

Supplying the Reference via Property or Method....209

Static Members....209

Choices, Choices....210

Baby Steps....210

24 The Catacombs of the Class....211

The Five Prototypes....211

Object-Oriented Design....214

Tic-Tac-Toe....216

25 Inheritance....218

Inheritance and the object Class....219

Choosing Base Classes....221

Constructors....222

Casting and Checking for Types....224

The protected Access Modifier....225

Sealed Classes....225

26 Polymorphism....227

Abstract Methods and Classes....229

New Methods....230

27 Interfaces....232

Defining Interfaces....233

Implementing Interfaces....234

Interfaces and Base Classes....235

Explicit Interface Implementations....235

Default Interface Methods....236

Supporting Default Interface Methods....237

Should I Use Default Interface Methods?....238

28 Structs....239

Memory and Constructors....240

Classes vs. Structs....241

Choosing to Make a Class or a Struct....242

Rules to Follow When Making Structs....244

Built-In Type Aliases....245

Boxing and Unboxing....246

29 Records....248

Records....248

String Representation....249

Value Semantics....249

Deconstruction....249

with Statements....249

Advanced Scenarios....250

Additional Members....250

Replacing Synthesized Members....250

Non-Positional Records....251

Struct- and Class-Based Records....251

Inheritance....252

When to Use a Record....252

30 Generics....253

The Motivation for Generics....253

Defining a Generic Type....256

Multiple Generic Type Parameters....257

Inheritance and Generic Types....257

Generic Methods....258

Generic Type Constraints....258

Multiple Constraints....260

Constraints on Methods....260

The default Operator....260

31 The Fountain of Objects....262

The Main Challenge....263

Expansions....265

32 Some Useful Types....268

The Random Class....269

The DateTime Struct....270

The TimeSpan Struct....271

The Guid Struct....272

The List Class....273

Creating List Instances....273

Indexing....273

Adding and Removing Items from List....274

foreach Loops....274

Other Useful Things....275

The IEnumerable Interface....276

The Dictionary Class....277

Types Besides string....278

Dictionary Keys Should Not Change....278

The Nullable Struct....279

ValueTuple Structs....279

The StringBuilder Class....280

Part 3: Advanced Topics....282

33 Managing Larger Programs....284

Using Multiple Files....284

Namespaces and using Directives....285

Advanced using Directive Features....287

Global using Directives....287

Static using Directives....287

Name Conflicts and Aliases....287

Putting Types into Namespaces....288

Namespace Naming Conventions....289

Traditional Entry Points....289

34 Methods Revisited....292

Optional Arguments....292

Named Arguments....293

Variable Number of Parameters....293

Combinations....294

Passing by Reference....294

Output Parameters....296

There’s More!....297

Deconstructors....297

Extension Methods....298

35 Error Handling and Exceptions....301

Handling Exceptions....302

Handling Specific Exception Types....303

Using the Exception Object....304

Throwing Exceptions....304

The finally Block....305

Exception Guidelines....306

What to Handle....306

Only Handle What You Can Fix....306

Use the Right Exception Type....306

Avoid Pokémon Exception Handling....307

Avoid Eating Exceptions....307

Avoid Throwing Exceptions When Possible....307

Come Back with Your Shield or On It....308

Advanced Exception Handling....309

Stack Traces....309

Rethrowing Exceptions....309

Inner Exceptions....310

Exception Filters....310

36 Delegates....312

Delegate Basics....312

The Action, Func, and Predicate Delegates....315

MulticastDelegate and Delegate Chaining....316

37 Events....317

C# Events....317

Events with Parameters....319

Null Events....320

Event Leaks....321

EventHandler and Friends....321

Custom Event Accessors....322

38 Lambda Expressions....324

Lambda Expression Basics....324

The Origin of the Name Lambda....325

Multiple and Zero Parameters....326

When Type Inference Fails....326

Discards....326

Lambda Statements....326

Closures....327

39 Files....329

The File Class....329

String Manipulation....331

Other String Parsing Methods....332

File System Manipulation....333

The Directory Class....333

The Path Class....334

There’s More!....334

Other Ways to Access Files....334

Streams....334

Find a Library....336

40 Pattern Matching....337

The Constant Pattern and the Discard Pattern....338

The Monster Scoring Problem....338

The Type and Declaration Patterns....339

Case Guards....340

The Property Pattern....340

Nested Patterns....341

Relational Patterns....341

The and, or, and not Patterns....342

The Positional Pattern....342

Deconstructors and the Positional Pattern....343

The var Pattern....343

Parenthesized Patterns....343

Patterns with Switch Statements and the is Keyword....343

Switch Statements....343

The is Keyword....344

Summary....344

41 Operator Overloading....346

Operator Overloading....347

Defining an Operator Overload....347

When to Overload Operators....348

Indexers....348

Index Initializer Syntax....349

Custom Conversions....350

The Pitfalls of Custom Conversions and Some Alternatives....351

42 Query Expressions....354

Queries and IEnumerable....355

Sample Classes....355

Query Expression Basics....355

Filtering....356

Ordering....357

Method Call Syntax....357

Unique Methods....358

Advanced Queries....359

Multiple from Clauses....359

Joining Multiple Collections Together....359

The let Clause....360

Continuation Clauses....360

Grouping....360

Group Joins....361

Deferred Execution....361

LINQ to SQL....362

43 Threads....364

The Basics of Threads....364

Using Threads....365

Sharing Data with a Thread....366

Sleeping....367

Thread Safety....368

Locks....369

44 Asynchronous Programming....372

A Sample Problem....373

Threads and Callbacks....373

Using Tasks....374

Task and Task Basics....374

The async and await Keywords....376

Who Runs My Code?....377

Some Additional Details....379

Exceptions....379

Cancellation....379

Awaitables....379

Limitations....380

More Information....380

45 Dynamic Objects....382

Dynamic Type Checking....383

Dynamic Objects....383

Emulating Dynamic Objects with Dictionaries....384

Using ExpandoObject....384

Extending DynamicObject....385

When to Use Dynamic Object Variations....386

46 Unsafe Code....388

Unsafe Contexts....389

Pointer Types....389

Fixed Statements....390

Stack Allocations....391

Fixed-Size Arrays....391

The sizeof Operator....391

The nint and nuint Types....392

Calling Native Code with Platform Invocation Services....392

47 Other Language Features....394

Iterators and the yield Keyword....395

Async Enumerables....396

Constants....396

Attributes....397

Attributes on Everything....398

Attributes are Classes....398

Reflection....399

The nameof Operator....400

Nested Types....400

Even More Accessibility Modifiers....401

Bit Manipulation....401

Bitshift Operators....402

Bitwise Logical Operators....403

Flags Enumerations....404

using Statements and the IDisposable Interface....405

Preprocessor Directives....406

#warning and #error....406

#region and #endregion....406

Working with Conditional Compilation Symbols....407

Command-Line Arguments....408

Partial Classes....408

Partial Methods....409

The Notorious goto Keyword....409

Generic Covariance and Contravariance....410

Checked and Unchecked Contexts....412

Volatile Fields....413

48 Beyond a Single Project....414

Outgrowing a Single Project....414

NuGet Packages....417

49 Compiling in Depth....420

Hardware....420

Assembly....422

Programming Languages....422

Instruction Set Architectures....423

Virtual Machines and Runtimes....423

50 .NET....425

The History of .NET....425

The Components of .NET....426

Common Infrastructure....426

Common Intermediate Language....426

The Common Language Runtime....426

The .NET Software Development Kit....427

Base Class Library....427

App Models....428

Web App Models....428

Mobile App Models....428

Desktop App Models....428

Game Development....429

51 Publishing....430

Build Configurations....430

Publish Profiles....431

.pubxml Files....434

Publishing with a Profile....434

After Publishing....434

Part 4: The Endgame....436

52 The Final Battle....438

Overview....439

Core Challenges....440

Expansions....444

53 Into Lands Uncharted....450

Keep Learning....450

Other Frameworks and Libraries....450

Other Topics....451

Make Software....451

Do the Side Quests....451

Where Do I Go to Get Help?....451

Parting Words....452

Part 5: Bonus Levels....454

A Visual Studio Overview....456

Windows....456

The Code Window....457

Code Navigation....458

IntelliSense....458

Quick Actions....459

The Solution Explorer....460

The Properties Window....461

The Error List....461

Other Windows....461

The Options Dialog....462

B Compiler Errors....463

Code Problems: Errors, Warnings, and Messages....463

How to Resolve Compiler Errors....464

Compile Often....464

Use a Quick Action....464

Make Sure You Understand the Key Parts of the Error Message....464

Backup or Undo....464

Be Cautious with Internet Code....465

Be Careful Transcribing Code....465

Fix the Errors that Make Sense....465

Look Around....465

Take a Break....465

Read the Documentation....465

Ask for Help....466

Common Compiler Errors....466

“The name ‘x’ doesn’t exist in the current context”....466

“) expected”, “} expected”, “] expected”, and “; expected”....466

Cannot convert type ‘x’ to ‘y’....467

“not all code paths return a value”....467

“The type or namespace name ‘x’ could not be found”....467

C Debugging Your Code....468

Some Broken Sample Code....468

Print Debugging....469

Using a Debugger....469

Breakpoints....470

Stepping Through Code....471

Edit and Continue and Hot Reload....472

Breakpoint Conditions and Actions....472

Glossary....473

Index....489

Like an entertaining video game, programming is often a challenging but always rewarding experience. This book shakes off the dusty, dull and dry typical programming book, replacing it with something more exciting and interesting: a little humor, a relaxed tone and examples with dragons and asteroids instead of bank accounts and employees.And since you learn to program by doing, not just reading, this book contains more than 100 practical programming tasks. You will be creating software, not just reading about it. By completing tasks, you will earn experience points, increase your level and become a real C# programmer!This book covers the C# language from scratch. This does not mean that you have been programming for many years, but you also do not give up on interesting and powerful language features.The journey begins with preparing for C# programming.Then we'll learn the basic mechanics of C#: operators, expressions, variables, if statements, loops, and methods.Next, we will delve into a powerful and central feature of C#: object-oriented programming, which is an important tool needed to create larger programs.Next, we'll look at the advanced features of C# that make the language unique, elegant, and powerful.With this book as a companion, you will soon set out to save the world (or conquer it) with your own C# programs!The fifth edition has been updated for C#10, .NET 6 and Visual Studio 2022.