C++20 — The Big Four

Year: 2020 · Concepts: 284 (39 core + 245 STL)

C++20 is the largest update to C++ since C++11. It introduces four landmark features — Concepts, Ranges, Coroutines, and Modules — alongside dozens of smaller improvements.

Sections

• Core Language (39 concepts) — Concepts, coroutines, modules, consteval, constinit, three-way comparison, designated initializers.
• STL & Library (245 concepts) — Ranges library, std::span, std::format, std::jthread, std::barrier, std::latch, std::source_location, and much more.

The Big Four

1. Concepts

Type constraints for templates — readable, composable, and compiler-checked:

template<typename T>
concept Addable = requires(T a, T b) { a + b; };

2. Ranges

Lazy, composable view pipelines over sequences:

auto evens = views::iota(1, 100) | views::filter([](int n) { return n % 2 == 0; });

3. Coroutines

Suspendable functions with co_await, co_yield, co_return:

generator<int> fibonacci() {
  int a = 0, b = 1;
  while (true) { co_yield a; auto c = a + b; a = b; b = c; }
}

4. Modules

Replacing #include with proper module imports:

import std.core;

Navigation

Section	Concepts	Link
Core Language	39	Browse →
STL & Library	245	Browse →