space-efficient, very time-efficient • Sorted arrays: binary_search, lower_bound, equal_range • Now you can use constexpr algorithms • Easy: static_assert with constexpr is_sorted • string_view is also constexpr; not limited to numeric data • More advanced: constexpr sort your lookup tables14 static_assert is_sorted • Compile-time evaluation = no run-time codegen, even in debug builds #include #include static constexpr array skipped_extensions{".dll"sv, ".exe"sv, ".obj"sv}; static_assert(ranges::is_sorted(skipped_extensions)); for (const auto& ent : filesystem::recursive_directory_iterator{"."})

(similar to std::map)  unique keys (flat_map)  fast retrieval of values based on a key  Keys are sorted  Keys and values are stored in separate sequence containers, e.g. vectors or deques std::flat_map