C++ 2017

Non-owning reference to a string-like sequence. Ideal for function parameters.

Allows declaring a variable scoped to the statement. c++ 2017

std::optional<int> find_user_id(bool logged_in) if (logged_in) return 42; return std::nullopt; // No value Non-owning reference to a string-like sequence

Memory resources for container allocators, enabling custom memory management without recompiling container code. find_user_id(bool logged_in) if (logged_in) return 42

sum(1, 2, 3, 4, 5); // returns 15

: Finally integrated into the standard library, providing a cross-platform way to handle paths, directories, and file metadata.