C++20
Close
    • C++20
    • Reader Testimonials
    • Introduction
    • Conventions
    • Source Code
    • How should you read the Book?
    • Personal Notes
    • 1. Historical Context
    • 1.1 C++98
    • 1.2 C++03
    • 1.3 TR1
    • 1.4 C++11
    • 1.5 C++14
    • 1.6 C++17
    • 2.1 Stage 3
    • 2.2 Stage 2
    • 2.3 Stage 1
    • 3.1 The Big Four
    • 3.2 Core Language
    • 3.3 The Standard Library
    • 3.4 Concurrency
    • 4.1 Concepts
    • 4.2 Modules
    • 4.3 Equality Comparison and Three-Way Comparison
    • 4.4 Designated Initialization
    • 4.5 consteval and constinit
    • 4.6 Template Improvements
    • 4.7 Lambda Improvements
    • 4.8 New Attributes
    • 4.9 Further Improvements
    • 5.1 The Ranges Library
    • 5.2 std::span
    • 5.3 Container and Algorithm Improvements
    • 5.4 Arithmetic Utilities
    • 5.5 Formatting Library
    • 5.6 Calendar and Time Zones
    • 5.7 Further Improvements
    • 6.1 Coroutines
    • 6.2 Atomics
    • 6.3 Semaphores
    • 6.4 Latches and Barriers
    • 6.5 Cooperative Interruption
    • 6.6 std::jthread
    • 6.7 Synchronized Output Streams
    • 7.1 Fast Synchronization of Threads
    • 7.2 Variations of Futures
    • 7.3 Modification and Generalization of a Generator
    • 7.4 Various Job Workflows
    • Epilogue
    • 8. C++23 and Beyond
    • 8.1 C++23
    • 8.2 C++23 or Later
    • 8.3 Further Information about C++23
    • 10.1 Aggregate
    • 10.2 Automatic Storage Duration
    • 10.3 Callable
    • 10.4 Callable Unit
    • 10.5 Concurrency
    • 10.6 Critical Section
    • 10.7 Data Race
    • 10.8 Deadlock
    • 10.9 Dynamic Storage Duration
    • 10.10 Eager Evaluation
    • 10.11 Executor
    • 10.12 Function Objects
    • 10.13 Lambda Expressions
    • 10.14 Lazy Evaluation
    • 10.15 Literal Type
    • 10.16 Lock-free
    • 10.17 Lost Wakeup
    • 10.18 Math Laws
    • 10.19 Memory Location
    • 10.20 Memory Model
    • 10.21 Non-blocking
    • 10.22 Object
    • 10.23 Parallelism
    • 10.24 POD (Plain Old Data)
    • 10.25 Predicate
    • 10.26 RAII
    • 10.27 Race Conditions
    • 10.28 Regular Type
    • 10.29 Scalar Type
    • 10.30 SemiRegular
    • 10.31 Short-Circuit Evaluation
    • 10.32 Standard-Layout Type
    • 10.33 Static Storage Duration
    • 10.34 Spurious Wakeup
    • 10.35 The Big Four
    • 10.36 The Big Six
    • 10.37 Thread
    • 10.38 Thread Storage Duration
    • 10.39 Time Complexity
    • 10.40 Translation Unit
    • 10.41 Trivial Type
    • 10.42 Undefined Behavior
    • Index

About C++

1. Historical Context

C++20 is the next big C++ standard after C++11. Like C++11, C++20 changes the way we program in modern C++. This change mainly results from the addition of Concepts, Modules, Ranges, and Coroutines to the language. To understand this next big step in the evolution of C++, let me write a few words about the historical context of C++20.

C++ History

C++ History

C++ is about 40 years old. Here is a brief overview of what has changed in the previous years.

1.1 C++98

At the end of the 80’s, Bjarne Stroustrup and Margaret A. Ellis wrote their famous book Annotated C++ Reference Manual (ARM). This book served two purposes, to define the functionality of C++ in a world with many implementations, and to provide the basis for the first C++ standard C++98 (ISO/IEC 14882). Some of the essential features of C++98 were: templates, the Standard Template Library (STL) with its containers, and algorithms, strings, and IO streams.

1.2 C++03

With C++03 (14882:2003), C++98 received a technical correction, so small that there is no place on the timeline above. In the community, C++03, which includes C++98, is called legacy C++.

1.3 TR1

In 2005, something exciting happened. The so-called Technical Teport 1 (TR1) was published. TR1 was a big step toward C++11 and, therefore, towards Modern C++. TR1 (TR 19768) is based on the Boost project, which was founded by members of the C++ standardization committee. TR1 had 13 libraries that were destined to become part of the C++11 standard. For example, the regular expression library, the random number library, smart pointers and hashtables. Only the so-called special mathematical functions had to wait until C++17.

1.4 C++11

We call the C++11 standard Modern C++. The name Modern C++ is also used for C++14 and C++17. C++11 introduced many features that fundamentally changed the way we program in C++. For example, C++11 had the additions of TR1, but also move semantics, perfect forwarding, variadic templates, and constexpr. But that was not all. With C++11, we also got, for the first time, a memory model as the fundamental basis of threading and the standardization of a threading API.

1.5 C++14

C++14 is a small C++ standard. It brought read-writer locks, generalized lambdas, and extended constexpr functions.

1.6 C++17

C++17 is neither a big nor a small C++ standard. It has two outstanding features: the parallel STL and the standardized filesystem API. About 80 algorithms of the Standard Template Library can be executed in parallel or vectorized. As with C++11, the boost libraries were highly influential for C++17. Boost provided the filesystem library and new data types: std::string_view, std::optional, std::variant, and std::any.

Community Questions