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Favourite C++ features

C++17

  • Boost filesystem
  • execution policy: parallel algorithm support for range-based for loops - potential for easily parallelsing existing code
  • structured bindings
  • clamp
  • std::optional
  • [[maybe_unused]]

C++20

Concepts

  • Concepts are a revolutionary approach for writing templates! They allow you to put constraints on template parameters that improve the readability of code, speed up compilation time, and give better error messages.

C++20 gives us language support (new keywords - requires, concept) and a set of predefined concepts from the Standard Library.

In other words, you can restrict template parameters with a “natural” and easy syntax. Before C++20, there were various ways to add such constraints. See my other post Simplify Code with if constexpr and Concepts in C++17/C++20 - C++ Stories.

https://www.cppstories.com/2021/concepts-intro/

template <typename T>
void print(const std::vector<T>& vec) {
for (size_t i = 0; auto& elem : vec)
std::cout << elem << (++i == vec.size() ? "n" : ", ");
}

void print2(const std::vector<auto>& vec) {
for (size_t i = 0; auto& elem : vec)
std::cout << elem << (++i == vec.size() ? "n" : ", ");
}

Ranges and views

The ranges library provides components for dealing with ranges of elements, including a variety of view adapters: immutable views of things; a nod to strongly typed, const languages like Haskell, composing syntax.

Coroutines

A new stackless threading model that also allows lazy evaluation of infinite sequences.

Misc

  • contains() to check if a key is present in an associate container, rather than count() or find() which always search the whole container
  • spaceship operator
  • range based for loops with initialiser
  • bit header
  • https://en.cppreference.com/w/cpp/utility/source_location
  • https://en.cppreference.com/w/cpp/numeric/constants

Wish list

See the compiler support matrix.

  • std::format
  • modules - wait for clang12, gcc11

Modules

Look interesting but not available until clang-12.

  • https://www.bfilipek.com/2018/11/parallel-alg-perf.html
  • https://gcc.gnu.org/wiki/cxx-modules
  • https://clang.llvm.org/docs/Modules.html
  • https://vector-of-bool.github.io/2019/03/10/modules-1.html
  • https://en.cppreference.com/w/cpp/language/modules