24 Containers library [containers]

24.4 Associative containers [associative]

24.4.4 Class template map [map]

24.4.4.2 Constructors, copy, and assignment [map.cons]

explicit map(const Compare& comp, const Allocator& = Allocator());
Effects: Constructs an empty map using the specified comparison object and allocator.
Complexity: Constant.
template<class InputIterator> map(InputIterator first, InputIterator last, const Compare& comp = Compare(), const Allocator& = Allocator());
Effects: Constructs an empty map using the specified comparison object and allocator, and inserts elements from the range [first, last).
Complexity: Linear in N if the range [first, last) is already sorted using comp and otherwise , where N is last - first.
template<container-compatible-range<value_type> R> map(from_range_t, R&& rg, const Compare& comp = Compare(), const Allocator& = Allocator());
Effects: Constructs an empty map using the specified comparison object and allocator, and inserts elements from the range rg.
Complexity: Linear in N if rg is already sorted using comp and otherwise , where N is ranges​::​distance(rg).