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std::set(3) C++ Standard Libary std::set(3) NAME std::set - std::set Synopsis Defined in header <set> template< class Key, class Compare = std::less<Key>, (1) class Allocator = std::allocator<Key> > class set; namespace pmr { template< class Key, class Compare = std::less<Key> (2) (since C++17) > using set = std::set<Key, Compare, std::pmr::polymorphic_allocator<Key>>; } std::set is an associative container that contains a sorted set of unique objects of type Key. Sorting is done using the key comparison function Compare. Search, removal, and insertion operations have logarithmic complexity. Sets are usually implemented as Redblack trees. Everywhere the standard library uses the Compare requirements, uniqueness is determined by using the equivalence relation. In imprecise terms, two objects a and b are considered equivalent if neither compares less than the other: !comp(a, b) && !comp(b, a). std::set meets the requirements of Container, AllocatorAwareCon- tainer, AssociativeContainer and ReversibleContainer. Template parameters This section is incomplete Reason: Add descriptions of the template parameters. Member types Member type Definition key_type Key value_type Key size_type Unsigned integer type (usually std::size_t) difference_type Signed integer type (usually std::ptrdiff_t) key_compare Compare value_compare Compare allocator_type Allocator reference value_type& const_reference const value_type& Allocator::pointer (until C++11) pointer std::allocator_traits<Allocator>::pointer (since C++11) Allocator::const_pointer (until C++11) const_pointer std::allocator_traits<Alloca- tor>::const_pointer (since C++11) iterator Constant LegacyBidirectionalIterator to value_type const_iterator LegacyBidirectionalIterator to const value_type reverse_iterator std::reverse_iterator<iterator> const_reverse_iterator std::reverse_iterator<const_iterator> node_type (since C++17) a specialization of node handle represent- ing a container node type describing the result of inserting a node_type, a specialization of template<class Iter, class NodeType> struct /*unspecified*/ insert_return_type (since { C++17) Iter position; bool inserted; NodeType node; }; instantiated with template arguments iter- ator and node_type. Member functions constructor constructs the set (public member function) destructor destructs the set (public member function) operator= assigns values to the container (public member function) get_allocator returns the associated allocator (public member function) Iterators begin returns an iterator to the beginning cbegin (public member function) (C++11) end returns an iterator to the end cend (public member function) (C++11) rbegin returns a reverse iterator to the beginning crbegin (public member function) (C++11) rend returns a reverse iterator to the end crend (public member function) (C++11) Capacity empty checks whether the container is empty (public member function) size returns the number of elements (public member function) max_size returns the maximum possible number of elements (public member function) Modifiers clear clears the contents (public member function) inserts elements insert or nodes (since C++17) (public member function) insert_range inserts a range of elements (C++23) (public member function) emplace constructs element in-place (C++11) (public member function) emplace_hint constructs elements in-place using a hint (C++11) (public member function) erase erases elements (public member function) swap swaps the contents (public member function) extract extracts nodes from the container (C++17) (public member function) merge splices nodes from another container (C++17) (public member function) Lookup count returns the number of elements matching specific key (public member function) find finds element with specific key (public member function) contains checks if the container contains element with specific key (C++20) (public member function) equal_range returns range of elements matching a specific key (public member function) lower_bound returns an iterator to the first element not less than the given key (public member function) upper_bound returns an iterator to the first element greater than the given key (public member function) Observers key_comp returns the function that compares keys (public member function) value_comp returns the function that compares keys in objects of type value_type (public member function) Non-member functions operator== operator!= operator< operator<= operator> operator>= lexicographically compares the values of two sets operator<=> (function template) (removed in C++20) (removed in C++20) (removed in C++20) (removed in C++20) (removed in C++20) (C++20) std::swap(std::set) specializes the std::swap algorithm (function template) erase_if(std::set) erases all elements satisfying specific criteria (C++20) (function template) Deduction guides (since C++17) Notes The member types iterator and const_iterator may be aliases to the same type. This means defining a pair of function overloads using the two types as parameter types may violate the One Definition Rule. Since iterator is convertible to const_iterator, a single function with a const_iterator as parameter type will work instead. Feature-test macro Value Std Feature __cpp_lib_containers_ranges 202202L (C++23) Ranges construction and insertion for containers Example This section is incomplete Reason: no example Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Cor- rect behavior LWG 103 C++98 iterator allows modification of keys itera- tor made constant Key was not required to be LWG 230 C++98 CopyConstructible Key is also required to (a key of type Key might not be able to be CopyConstructible be constructed) Categories: * Todo with reason * Todo no example http://cppreference.com 2024.06.10 std::set(3)
NAME | Synopsis | Template parameters | Member types | Member functions | Iterators | Capacity | Modifiers | Lookup | Observers | Non-member functions | Notes | Example | Categories:
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