C++20 STL Cookbook: Leverage the latest features of the STL to solve real-world problems

Cover....1

Title Page....2

Copyright and Credits....3

Contributors....4

Table of Contents....6

Preface....14

Chapter 1: New C++20 Features....24

Technical requirements....25

Format text with the new format library....25

How to do it…....26

How it works…....27

There's more…....29

Use compile-time vectors and strings with constexpr....30

How to do it…....31

How it works…....31

Safely compare integers of different types....32

How to do it…....33

How it works…....33

Use the "spaceship" operator <=> for three-way comparisons....34

How to do it…....35

How it works…....37

There's more…....37

Easily find feature test macros with the header....39

How to do it…....39

How it works…....40

Create safer templates with concepts and constraints....40

How to do it…....41

How it works…....43

There's more…....44

Avoid re-compiling template libraries with modules....46

How to do it…....46

How it works…....48

Create views into containers with ranges....51

How to do it…....52

How it works…....54

There's more…....56

Chapter 2: General STL Features....58

Technical requirements....58

Use the new span class to make your C-arrays safer....59

How to do it…....59

How it works…....60

Use structured binding to return multiple values....61

How to do it…....62

How it works…....64

Initialize variables within if and switch statements....66

How to do it…....66

How it works…....67

There's more…....68

Use template argument deduction for simplicity and clarity....69

How to do it…....69

How it works…....71

There's more…....73

Use if constexpr to simplify compile-time decisions....74

How to do it…....74

How it works…....75

Chapter 3: STL Containers....76

A quick overview of the STL container types....76

Sequential containers....76

Associative containers....77

Container adapters....78

Technical requirements....79

Use uniform erasure functions to delete items from a container....79

How to do it…....80

How it works…....82

Delete items from an unsorted vector in constant time....84

How to do it…....84

How it works…....86

Access vector elements directly and safely....87

How to do it…....87

How it works…....89

There's more…....89

Keep vector elements sorted....90

How to do it…....90

How it works…....92

There's more…....92

Efficiently insert elements into a map....93

How to do it…....94

How it works…....96

Efficiently modify the keys of map items....98

How to do it…....98

How it works…....101

There's more…....101

Use unordered_map with custom keys....102

How to do it…....102

How it works…....104

Use set to sort and filter user input....105

How to do it…....105

How it works…....106

A simple RPN calculator with deque....107

How to do it…....109

How it works…....113

There's more…....114

A word frequency counter with map....115

How to do it…....115

How it works…....119

Find long sentences with a vector of vectors....120

How to do it…....120

How it works…....123

A ToDo list using multimap....124

How to do it…....124

How it works…....126

Chapter 4: Compatible Iterators....128

Iterators are fundamental....128

Iterator categories....131

Iterator concepts....131

Technical requirements....134

Create an iterable range....135

How to do it…....135

How it works…....137

There's more…....138

Make your iterators compatible with STL iterator traits....138

How to do it…....139

How it works…....140

There's more…....140

Use iterator adapters to fill STL containers....141

How to do it…....141

How it works…....144

Create a generator as iterators....145

How to do it…....146

How it works…....148

There's more…....149

Use reverse iterator adapters to iterate backward....150

How to do it…....150

How it works…....152

Iterate objects of unknown length with a sentinel....153

How to do it…....154

How it works…....156

Build a zip iterator adapter....156

How to do it…....157

How it works…....161

There's more…....163

Create a random-access iterator....163

How to do it…....164

How it works…....169

Chapter 5: Lambda Expressions....170

Lambda expressions....170

Closures....171

Technical requirements....172

Use lambdas for scoped reusable code....173

How to do it…....173

How it works…....176

Use lambdas as predicates with the algorithm library....178

How to do it…....178

How it works…....180

Use std::function as a polymorphic wrapper....181

How to do it…....181

How it works…....183

There's more…....184

Concatenate lambdas with recursion....185

How to do it…....185

How it works…....186

Combine predicates with logical conjunction....187

How to do it…....187

How it works…....188

Call multiple lambdas with the same input....189

How to do it…....189

How it works…....190

Use mapped lambdas for a jump table....191

How to do it…....191

How it works…....192

Chapter 6: STL Algorithms....194

Technical requirements....195

Copy from one iterator to another....195

How to do it…....196

How it works…....198

Join container elements into a string....199

How to do it…....200

How it works…....202

There's more…....203

Sort containers with std::sort....203

How to do it…....204

How it works…....207

Modify containers with std::transform....208

How to do it…....208

How it works…....210

Find items in a container....211

How to do it…....211

How it works…....213

There's more…....214

Limit the values of a container to a range with std::clamp....214

How to do it…....214

How it works…....216

Sample data sets with std::sample....217

How to do it…....217

How it works…....220

Generate permutations of data sequences....220

How to do it…....221

How it works…....222

Merge sorted containers....223

How to do it…....223

How it works…....225

Chapter 7: Strings, Streams, and Formatting....226

String formatting....227

Technical requirements....228

Use string_view as a lightweight string object....228

How to do it…....228

How it works…....230

Concatenate strings....232

How to do it…....232

How it works…....234

There's more…....234

Why would I choose one over another?....238

Transform strings....238

How to do it…....239

How it works…....241

Format text with C++20's format library....241

How to do it…....242

How it works…....246

There's more…....247

Trim whitespace from strings....248

How to do it…....248

How it works…....249

Read strings from user input....250

How to do it…....251

How it works…....254

Count words in a file....254

How to do it…....254

How it works…....255

Initialize complex structures from file input....255

How to do it…....256

How it works…....258

There's more…....258

Customize a string class with char_traits....260

How to do it…....260

How it works…....263

There's more…....263

Parse strings with Regular Expressions....264

How to do it…....265

How it works…....266

Chapter 8: Utility Classes....268

Technical requirements....269

Manage optional values with std::optional....269

How to do it…....270

How it works…....272

There's more…....272

Use std::any for type safety....273

How to do it…....274

How it works…....275

Store different types with std::variant....276

Differences from the primitive union structure....276

How to do it…....277

How it works…....281

Time events with std::chrono....282

How to do it…....282

How it works…....287

Use fold expressions for variadic tuples....288

Fold expressions....288

How to do it…....290

How it works…....291

There's more…....292

Manage allocated memory with std::unique_ptr....293

How to do it…....294

How it works…....297

Share objects with std::shared_ptr....298

How to do it…....299

How it works…....302

Use weak pointers with shared objects....303

How to do it…....303

How it works…....305

There's more…....306

Share members of a managed object....307

How to do it…....307

How it works…....309

Compare random number engines....310

How to do it…....310

How it works…....314

There's more…....314

Compare random number distribution generators....315

How to do it…....315

How it works…....318

Chapter 9: Concurrency and Parallelism....320

Technical requirements....321

Sleep for a specific amount of time....321

How to do it…....321

How it works…....322

There's more…....323

Use std::thread for concurrency....323

How to do it…....323

How it works…....327

There's more…....328

Use std::async for concurrency....329

How to do it…....329

How it works…....333

Run STL algorithms in parallel with execution policies....335

How to do it…....335

How it works…....337

Share data safely with mutex and locks....338

How to do it…....338

How it works…....346

There's more…....346

Share flags and values with std::atomic....347

How to do it…....347

How it works…....349

There's more…....353

Initialize threads with std::call_once....354

How to do it…....354

How it works…....355

Use std::condition_variable to resolve the producer-consumer problem....356

How to do it…....356

How it works…....358

Implement multiple producers and consumers....360

How to do it…....360

How it works…....363

Chapter 10: Using the File System....366

Technical requirements....367

Specialize std::formatter for the path class....367

How to do it…....367

How it works…....369

Use manipulation functions with path....370

How to do it…....370

How it works…....373

List files in a directory....374

How to do it…....374

How it works…....383

There's more…....383

Search directories and files with a grep utility....384

How to do it…....385

How it works…....391

See also…....391

Rename files with regex and directory_iterator....391

How to do it…....391

How it works…....395

See also…....396

Create a disk usage counter....396

How to do it…....396

How it works…....401

Chapter 11: A Few More Ideas....402

Technical requirement....402

Create a trie class for search suggestions....403

How to do it…....403

How it works…....410

Calculate the error sum of two vectors....411

How to do it…....411

How it works…....413

There's more…....413

Build your own algorithm: split....414

How to do it…....415

How it works…....418

Leverage existing algorithms: gather....418

How to do it…....419

How it works…....422

Remove consecutive whitespace....422

How to do it…....422

How it works…....423

Convert numbers to words....424

How to do it…....425

How it works…....433

There's more…....433

Index....436

Other Books You May Enjoy....447

The C++20 STL Cookbook provides recipes to help you get the most out of the C++ STL (Standard Template Library), including new features introduced with C++20.

C++ is a rich and powerful language. Built upon C, with syntactic extensions for type safety, generic programming, and object-oriented programming, C++ is essentially a low-level language. The STL provides a broad set of higher-level classes, functions, and algorithms to make your programming job easier, more effective, and less prone to error.

I've often said that C++ is five languages cobbled into one. The formal specification includes 1) the entire C language, 2) C's cryptic-yet-powerful macro preprocessor, 3) a feature-rich class/object model, 4) a generic programming model called templates, and finally, built upon C++ classes and templates, 5) the STL.