C++17
C++17 (ISO/IEC 14882:2017) is a major update that introduces a large number of highly practical language features and library components, further improving the expressiveness and safety of C++.
Core Features
Language Level
| Feature | Description |
|---|
| Structured Bindings | auto [x, y] = pair; |
if constexpr | Compile-time branching, replacing SFINAE hacks |
| Fold Expressions | (args + ...) simplifies variadic templates |
| Class Template Argument Deduction (CTAD) | pair p(1, 2.0); no explicit template arguments needed |
| Inline Variables | The correct way to define global variables in header files |
| Nested Namespaces | namespace A::B::C {} |
[[nodiscard]] / [[maybe_unused]] / [[fallthrough]] | More attributes |
Standard Library Level
| Component | Description |
|---|
std::optional | Value-semantic container that may be empty |
std::variant | Type-safe union |
std::any | Container for any type |
std::string_view | Non-owning string view, zero-copy |
<filesystem> | Standardized filesystem operations |
| Parallel Algorithms | std::execution::par execution policies |
std::apply | Apply function to tuple |
std::byte | Type-safe byte type |
std::clamp | Numeric clamping |
std::invoke | Unified call syntax |
std::from_chars / std::to_chars | High-performance numeric conversion |
std::conjunction / disjunction / negation | Type trait logical composition |
Design Philosophy
The design philosophy of C++17 can be summarized as "practicality first":
- Eliminate boilerplate: Structured bindings and CTAD reduce redundant declarations
- Zero-overhead abstractions:
string_view and optional introduce no runtime overhead - Compile-time capabilities:
if constexpr makes template code more readable - Safety:
[[nodiscard]] helps catch ignored return values
Compiler Support
| Compiler | Full Support Version |
|---|
| GCC | 9+ |
| Clang | 8+ |
| MSVC | VS 2019 (16.0)+ |
Further Reading
