C++20 - The Complete Guide

C++20 - The Complete Guide
Contents
Preface
	An Experiment
	Versions of this Book
	Acknowledgments
About This Book
	What You Should Know Before Reading This Book
	Overall Structure of the Book
	How to Read This Book
	The Way I Implement
		Initializations
		Error Terminology
		Code Simplifications
	The C++ Standards
	Example Code and Additional Information
	Feedback
1 Comparisons and Operator <=>
	1.1 Motivation for Operator<=>
		1.1.1 Defining Comparison Operators Before C++20
		1.1.2 Defining Comparison Operators Since C++20
	1.2 Defining and Using Comparisons
		1.2.1 Using Operator<=>
		1.2.2 Comparison Category Types
		1.2.3 Using Comparison Categories with operator<=>
		1.2.4 Calling operator<=>
		1.2.5 Dealing with Multiple Ordering Criteria
	1.3 Defining operator<=> and operator==
		1.3.1 Defaulted operator<=>
		1.3.2 Defaulted operator<=> and Inheritance
	1.4 Overload Resolution with Rewritten Expressions
	1.5 Compatibility Issues with the Comparison Operators
	1.6 Afternotes
2 Placeholder Types for Function Parameters
	2.1 auto for Parameters of Ordinary Functions
		2.1.1 auto for Parameters of Member Functions
		2.1.2 auto Functions versus Lambdas
		2.1.3 auto for Parameters in Detail
	2.2 Other Placeholder Types for Parameters of Ordinary Functions
	2.3 Afternotes
3 Concepts and Requirements
	3.1 Motivating Example of Concepts and Requirements
		3.1.1 Improving the Template Step-by-Step
		3.1.2 The Whole Resulting Program
	3.2 Typical Application of Concepts and Requirements in Practice
		3.2.1 Requirements to Understand Code and Error Messages
		3.2.2 Requirements to Disable Generic Code
		3.2.3 Requirements to Use Different Statements
		3.2.4 The Example as a Whole
		3.2.5 Former Workarounds
	3.3 Constraints and Requirements in Detail
		3.3.1 Constraints
		3.3.2 Ad hoc Boolean Expressions
		3.3.3 requires Expressions
	3.4 Concepts in Detail
		3.4.1 Defining Concepts
		3.4.2 Special Abilities of Concepts
		3.4.3 Using Concepts as Type Constraints
	3.5 Subsuming Constraints and Concepts
		3.5.1 Indirect Subsumptions
	3.6 Semantic Constraints
	3.7 Design Guidelines for Concepts
		3.7.1 Dealing with Multiple Requirements
		3.7.2 Concepts versus Traits and Expressions
		3.7.3 When to Use if constexpr
	3.8 Other Stuff of Concepts
	3.9 Afternotes
4 Standard Concepts in Detail
	4.1 Overview of all Standard Concepts
		4.1.1 Header Files and Namespaces
	4.2 Language-Related Concepts
		4.2.1 Arithmetic Concepts
		4.2.2 Object Concepts
		4.2.3 Concepts for Relations between Types
		4.2.4 Comparison Concepts
	4.3 Concepts for Iterators and Ranges
		4.3.1 Concepts for Ranges and Views
		4.3.2 Concepts for Pointers-Like Objects
		4.3.3 Concepts for Iterators
		4.3.4 Iterator Concepts for Algorithms
	4.4 Concepts for Callables
		4.4.1 Basic Concepts for Callables
		4.4.2 Concepts for Callables Used by Iterators
	4.5 Auxiliary Concepts
		4.5.1 Concepts for Specific Type Attributes
		4.5.2 Concepts for Incrementable Types
	4.6 Afternotes
5 Ranges and Views
	5.1 A Tour of Ranges by Example
		5.1.1 Passing Containers to Algorithms as Ranges
		5.1.2 Algorithms with Requirements
		5.1.3 Views
		5.1.4 Sentinels
		5.1.5 Range Definitions with Sentinels and Counts
		5.1.6 Projections
		5.1.7 Utilities to Implement Code for Ranges
		5.1.8 Limitations and Drawbacks of Ranges
	5.2 Using Views
		5.2.1 Views from Ranges
		5.2.2 Pipelines for Temporary Ranges
		5.2.3 Lazy Evaluation
		5.2.4 Performance Issues with Filters
		5.2.5 Views and Pipelines with Write Access
		5.2.6 Write Access with Filter Views
	5.3 Borrowed Iterators and Ranges
		5.3.1 Borrowed Iterators
		5.3.2 Borrowed Ranges
	5.4 Ranges and const
		5.4.1 Views Remove the Propagation of const
		5.4.2 Bringing Back Deep Constness to Views
		5.4.3 Generic Code Should Take Ranges with Non-const &&
	5.5 Afternotes
6 Components for Ranges and View
	6.1 Major Range Adaptors
		6.1.1 Range Adaptor all()
		6.1.2 Range Adaptor counted()
		6.1.3 Range Adaptor common()
	6.2 New Iterators
		6.2.1 std::counted_iterator
		6.2.2 std::common_iterator
		6.2.3 std::default_sentinel
		6.2.4 std::unreachable_sentinel
	6.3 Helper Functions in std::ranges
	6.4 Helper Types in std::ranges
	6.5 Open
	6.6 Afternotes
7 View Types in Detail
	7.1 Overview of all Views
		7.1.1 Overview of Features That Create Views
		7.1.2 Overview of Modifying Views
	7.2 Base Classes for Views
	7.3 Creating Views to External Elements
		7.3.1 std::ranges::subrange
		7.3.2 std::ranges::ref_view
		7.3.3 std::ranges::common_view
	7.4 Generating Views
		7.4.1 std::ranges::iota_view
		7.4.2 std::ranges::single_view
		7.4.3 std::ranges::empty_view
		7.4.4 IStream View
		7.4.5 String View
	7.5 Filtering Views
		7.5.1 Take View
		7.5.2 Take-While View
		7.5.3 Drop View
		7.5.4 Drop-While View
		7.5.5 Filter View
	7.6 Transforming Views
		7.6.1 Transform View
		7.6.2 Elements View
		7.6.3 Keys View
		7.6.4 Values View
	7.7 Mutating Views
		7.7.1 std::ranges::reverse_view
	7.8 Views for Multiple Ranges
		7.8.1 Split and Lazy-Split View
		7.8.2 Join View
	7.9 Open
	7.10 Afternotes
8 Spans
	8.1 Using Spans
		8.1.1 Fixed and Dynamic Extent
		8.1.2 Example Using a Span with Fixed Extent
		8.1.3 Example Using a Span with a Dynamic Extent
	8.2 Spans Considered Harmful
	8.3 Design Aspects of Spans
		8.3.1 Performance of Spans
		8.3.2 const Correctness of Spans
		8.3.3 Using Spans as Parameters in Generic Code
	8.4 Span Operations
		8.4.1 Span Operations and Member Types Overview
	8.5 Afternotes
9 Non-Type Template Parameter (NTTP) Extensions
	9.1 New Types for Non-Type Template Parameters
		9.1.1 double Values as Non-Type Template Parameters
		9.1.2 Objects as Non-Type Template Parameters
		9.1.3 Lambdas as Non-Type Template Parameters
	9.2 Details of Floating-Point Values as NTTP\'s
	9.3 Details of Objects as NTTP\'s
	9.4 Afternotes
10 Compile-Time Computing
	10.1 Keyword constinit
		10.1.1 Using constinit in Practice
		10.1.2 How constinit Solves the Static Initialization Order Fiasco
	10.2 Keyword consteval
		10.2.1 A First consteval Example
		10.2.2 constexpr versus consteval
		10.2.3 Using consteval in Practice
		10.2.4 Compile-Time Value versus Compile-Time Context
	10.3 Relaxed Constraints for constexpr Functions
	10.4 std::is_constant_evaluated()
		10.4.1 std::is_constant_evaluated() in Detail
	10.5 Using Heap Memory, Vectors, and Strings at Compile Time
		10.5.1 Using Vectors at Compile Time
		10.5.2 Returning a Collection at Compile Time
		10.5.3 Using Strings at Compile Time
	10.6 Other constexpr Extensions
		10.6.1 constexpr Language Extensions
		10.6.2 constexpr Library Extensions
	10.7 Afternotes
11 Lambda Extensions
	11.1 Generic Lambdas with Template Parameters
		11.1.1 Using Template Parameters for Generic Lambdas in Practice
		11.1.2 Explicit Specification of Lambda Template Parameters
	11.2 Calling the Default Constructor of Lambdas
	11.3 Lambdas as Non-Type Template Parameters
	11.4 consteval Lambdas
	11.5 Changes for Capturing
		11.5.1 Capturing this and *this
		11.5.2 Capturing Structured Bindings
		11.5.3 Capturing Parameter Packs of Variadic Templates
	11.6 Afternotes
12 Other C++ Language Improvements
	12.1 New Character Type char8_t
		12.1.1 Changes in the C++ Standard Library for char8_t
		12.1.2 Broken Backward Compatibility
	12.2 Designated Initializers
	12.3 Implicit typename for Type Members of Template Parameters
		12.3.1 Rules for Implicit typename
	12.4 Afternotes
13 Formatted Output
	13.1 Formatted Output by Example
		13.1.1 Using std::format()
		13.1.2 Using std::format_to_n()
		13.1.3 Using std::format_to()
		13.1.4 Using std::formatted_size()
	13.2 Formatted Output in Detail
		13.2.1 General Format of Format Strings
		13.2.2 Standard Format Specifiers
		13.2.3 Width, Precision, and Fill Characters
		13.2.4 Format/Type Specifiers
	13.3 Error Handling
	13.4 Internationalization
	13.5 User-Defined Formatted Output
		13.5.1 Basic Formatter API
		13.5.2 Improved Parsing
		13.5.3 Parsing with the Help of Standard Formatters
	13.6 Afternotes
14 Dates and Time Zones for 
	14.1 Overview by Example
		14.1.1 Schedule a Meeting on the 5th of Every Month
		14.1.2 Schedule a Meeting Every First Monday
	14.2 Basic Chrono Concepts and Terminology
	14.3 Basic Chrono Extensions with C++20
		14.3.1 Duration Types
		14.3.2 Clocks
		14.3.3 Timepoint Types
		14.3.4 Calendrical Types
		14.3.5 Time Type hh_mm_ss
	14.4 Time Zones
		14.4.1 Characteristics of Time Zones
		14.4.2 Using Time Zones
	14.5 I/O with Chrono Types
		14.5.1 Default Output Formats
		14.5.2 Formatted Output
		14.5.3 Locale Dependent Output
		14.5.4 Formatted Input
	14.6 Using the Chrono Extensions in Practice
		14.6.1 Invalid Dates
		14.6.2 Dealing with months and years
		14.6.3 Parsing Time Points and Durations
		14.6.4 Dealing with Time Zone Abbreviations
		14.6.5 Custom Timezones
	14.7 Clocks in Detail
		14.7.1 Clocks with a Specified Epoch
		14.7.2 The Pseudo Clock local_t
		14.7.3 Dealing with Leap Seconds
		14.7.4 Conversions between Clocks
		14.7.5 Dealing with the File Clock
	14.8 Other New Chrono Features
	14.9 Afternotes
15 Coroutines
	15.1 What Are Coroutines?
	15.2 A First Coroutine Example
		15.2.1 Defining a Coroutine
	15.3 Further Coroutine Examples
		15.3.1 Coroutine with co_yield
		15.3.2 Coroutine with co_return
	15.4 Coroutines in Detail
	15.5 Afternotes
16 std::jthread and Stop Tokens
	16.1 Motivation for std::jthread
		16.1.1 The Problem of std::thread
		16.1.2 Using std::jthread
		16.1.3 Stop Tokens and Stop Callbacks
	16.2 Stop Sources and Stop Tokens
		16.2.1 Stop Sources and Stop Tokens in Detail
		16.2.2 Using Stop Callbacks
		16.2.3 Constraints and Guarantees of Stop Tokens
	16.3 std::jthread In Detail
		16.3.1 Using Stop Tokens with std::jthread
	16.4 Afternotes
17 Concurrency Features
	17.1 Thread Synchronization with Latches and Barriers
		17.1.1 Latches
		17.1.2 Barriers
	17.2 Semaphores
		17.2.1 Example of Using Counting Semaphores
		17.2.2 Example of Using Binary Semaphores
	17.3 Extensions for and New Atomic Types
	17.4 Atomic References with std::atomic_ref<>
		17.4.1 Atomic Shared Pointers
		17.4.2 Atomic Floating-Point Types
		17.4.3 Thread Synchronization with Atomic Types
		17.4.4 Extensions for std::atomic_flag
	17.5 Synchronized Output Streams
		17.5.1 Motivation of Synchronized Output Streams
		17.5.2 Using of Synchronized Output Streams
		17.5.3 Using Synchronized Output Streams for Files
		17.5.4 Using Synchronized Output Streams as Output Streams
		17.5.5 Synchronized Output Streams in Detail
	17.6 Afternotes
18 Other C++ Standard Library Improvements
	18.1 Updates for String Types
	18.2 String Members starts_with() and ends_with()
	18.3 Restricted String Member reserve()
	18.4 New Utility Functions
		18.4.1 ssize()
	18.5 std::source_location
	18.6 New Type Traits
		18.6.1 Type Traits is_bounded_array<> and is_unbounded_array
		18.6.2 Type Trait is_nothrow_convertible<>
		18.6.3 Type Trait is_layout_compatible<>
		18.6.4 Type Trait is_layout_pointer_interconvertible_base_of<>
		18.6.5 Type Trait remove_cvref<>
		18.6.6 Type Traits unwrap_reference<> and unwrap_ref_decay
		18.6.7 Type Trait common_reference<>
		18.6.8 Type Trait type_identity<>
		18.6.9 is_pointer_interconvertible_with_class<>() and is_corresponding_member<>()
	18.7 Mathematical Constants
	18.8 Utilities to Deal with Bits
		18.8.1 Bit Operations
		18.8.2 std::bit_cast<>()
		18.8.3 std::endian
	18.9 
	18.10 Afternotes
19 Modules
	19.1 Motivation of Modules by a First Example
		19.1.1 Implementing and Exporting a Module
		19.1.2 Importing and Using a Module
		19.1.3 Reachable versus Visible
		19.1.4 Modules and Namespaces
		19.1.5 Modules and Filenames
	19.2 Modules with Multiple Files
		19.2.1 Module Units
		19.2.2 A Module with Multiple Implementation Units
		19.2.3 Internal Module Partitions
		19.2.4 Interface Partitions
		19.2.5 How Modules Replace Traditional Code
		19.2.6 Module Declaration/Export in Detail
		19.2.7 Module Import in Detail
		19.2.8 Dealing with Module Files in Compilers
	19.3 Exporting
	19.4 Importing
	19.5 Private Module Fragments
	19.6 Dealing with Header Files
	19.7 Status of Modules in Practice
	19.8 Afternotes
Glossary
	A
	C
	F
	G
	I
	L
	P
	R
	S
	U
	V
	X
Index
	A
	B
	C
	D
	E
	F
	G
	H
	I
	J
	K
	L
	M
	N
	O
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	T
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	W
	X
	Y
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