C++20 Features
Master C++20's major features — concepts, ranges, coroutines, modules, and three-way comparison that fundamentally improve C++ development.
55 min•By Priygop Team•Last updated: Feb 2026
C++20 Big Four
- Concepts: Constrain templates with readable requirements — template<typename T> requires Sortable<T> void sort(T& container). Replaces SFINAE with clear error messages
- Ranges: Composable, lazy algorithms — auto result = vec | views::filter(is_even) | views::transform(square) | views::take(5). Pipelines instead of iterator pairs
- Coroutines: Functions that can suspend and resume — co_await, co_yield, co_return. Enable generators, async I/O, and lazy sequences without threads
- Modules: Replace #include with import statements — import std; instead of #include <iostream>. Faster compilation, better encapsulation, no macro pollution
- Three-Way Comparison (Spaceship Operator <=>): auto operator<=>(const MyClass&) const = default; — generates all 6 comparison operators automatically
- Designated Initializers: Point p = {.x = 1, .y = 2}; — initialize struct members by name. Clearer than positional initialization
C++20 in Practice
- std::format: Type-safe string formatting — auto s = std::format('Hello, {}! You are {} years old.', name, age). Replaces printf and stringstream
- std::span<T>: Non-owning view of contiguous memory — replaces pointer+size pairs. void process(std::span<int> data) accepts arrays, vectors, and C arrays
- Calendar & Time Zones: Proper date/time handling — year_month_day, time zone conversions, formatting. No more manual time calculations
- std::jthread: Automatically joining thread — destructor calls join(). Supports cooperative cancellation with stop_token. Replaces std::thread + manual join
- consteval & constinit: consteval forces compile-time evaluation (constants generated at compile time). constinit ensures static init order (no SIOF bugs)