std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >(3) Library Functions Manual NAME std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc > - A standard container composed of unique keys (containing at most one of each key value) that associates values of another type with the keys. SYNOPSIS #include Public Types using insert_return_type using node_type typedef _Hashtable::key_type key_type Public typedefs. typedef _Hashtable::value_type value_type Public typedefs. typedef _Hashtable::mapped_type mapped_type Public typedefs. typedef _Hashtable::hasher hasher Public typedefs. typedef _Hashtable::key_equal key_equal Public typedefs. typedef _Hashtable::allocator_type allocator_type Public typedefs. typedef _Hashtable::pointer pointer Iterator-related typedefs. typedef _Hashtable::const_pointer const_pointer Iterator-related typedefs. typedef _Hashtable::reference reference Iterator-related typedefs. typedef _Hashtable::const_reference const_reference Iterator-related typedefs. typedef _Hashtable::iterator iterator Iterator-related typedefs. typedef _Hashtable::const_iterator const_iterator Iterator-related typedefs. typedef _Hashtable::local_iterator local_iterator Iterator-related typedefs. typedef _Hashtable::const_local_iterator const_local_iterator Iterator-related typedefs. typedef _Hashtable::size_type size_type Iterator-related typedefs. typedef _Hashtable::difference_type difference_type Iterator-related typedefs. Public Member Functions unordered_map ()=default Default constructor. template unordered_map (_InputIterator __first, _InputIterator __last, size_type __n, const allocator_type &__a) template unordered_map (_InputIterator __first, _InputIterator __last, size_type __n, const hasher &__hf, const allocator_type &__a) template unordered_map (_InputIterator __first, _InputIterator __last, size_type __n=0, const hasher &__hf=hasher(), const key_equal &__eql=key_equal(), const allocator_type &__a=allocator_type()) Builds an unordered_map from a range. unordered_map (const allocator_type &__a) Creates an unordered_map with no elements. unordered_map (const unordered_map &)=default Copy constructor. unordered_map (const unordered_map &__umap, const allocator_type &__a) unordered_map (initializer_list< value_type > __l, size_type __n, const allocator_type &__a) unordered_map (initializer_list< value_type > __l, size_type __n, const hasher &__hf, const allocator_type &__a) unordered_map (initializer_list< value_type > __l, size_type __n=0, const hasher &__hf=hasher(), const key_equal &__eql=key_equal(), const allocator_type &__a=allocator_type()) Builds an unordered_map from an initializer_list. unordered_map (size_type __n, const allocator_type &__a) unordered_map (size_type __n, const hasher &__hf, const allocator_type &__a) unordered_map (size_type __n, const hasher &__hf=hasher(), const key_equal &__eql=key_equal(), const allocator_type &__a=allocator_type()) Default constructor creates no elements. unordered_map (unordered_map &&)=default Move constructor. unordered_map (unordered_map &&__umap, const allocator_type &__a) noexcept(noexcept(_Hashtable(std::move(__umap._M_h), __a))) iterator begin () noexcept local_iterator begin (size_type __n) Returns a read/write iterator pointing to the first bucket element. size_type bucket (const key_type &__key) const size_type bucket_count () const noexcept Returns the number of buckets of the unordered_map. size_type bucket_size (size_type __n) const void clear () noexcept template std::pair< iterator, bool > emplace (_Args &&... __args) Attempts to build and insert a std::pair into the unordered_map. template iterator emplace_hint (const_iterator __pos, _Args &&... __args) Attempts to build and insert a std::pair into the unordered_map. bool empty () const noexcept Returns true if the unordered_map is empty. iterator end () noexcept local_iterator end (size_type __n) Returns a read/write iterator pointing to one past the last bucket elements. size_type erase (const key_type &__x) Erases elements according to the provided key. iterator erase (const_iterator __first, const_iterator __last) Erases a [__first,__last) range of elements from an unordered_map. node_type extract (const key_type &__key) Extract a node. node_type extract (const_iterator __pos) Extract a node. allocator_type get_allocator () const noexcept Returns the allocator object used by the unordered_map. hasher hash_function () const Returns the hash functor object with which the unordered_map was constructed. template void insert (_InputIterator __first, _InputIterator __last) A template function that attempts to insert a range of elements. iterator insert (const_iterator, node_type &&__nh) Re-insert an extracted node. void insert (initializer_list< value_type > __l) Attempts to insert a list of elements into the unordered_map. insert_return_type insert (node_type &&__nh) Re-insert an extracted node. template pair< iterator, bool > insert_or_assign (const key_type &__k, _Obj &&__obj) Attempts to insert a std::pair into the unordered_map. template iterator insert_or_assign (const_iterator __hint, const key_type &__k, _Obj &&__obj) Attempts to insert a std::pair into the unordered_map. template iterator insert_or_assign (const_iterator __hint, key_type &&__k, _Obj &&__obj) template pair< iterator, bool > insert_or_assign (key_type &&__k, _Obj &&__obj) key_equal key_eq () const Returns the key comparison object with which the unordered_map was constructed. float load_factor () const noexcept Returns the average number of elements per bucket. size_type max_bucket_count () const noexcept Returns the maximum number of buckets of the unordered_map. float max_load_factor () const noexcept Returns a positive number that the unordered_map tries to keep the load factor less than or equal to. void max_load_factor (float __z) Change the unordered_map maximum load factor. size_type max_size () const noexcept Returns the maximum size of the unordered_map. template void merge (unordered_map< _Key, _Tp, _H2, _P2, _Alloc > &&__source) template void merge (unordered_map< _Key, _Tp, _H2, _P2, _Alloc > &__source) template void merge (unordered_multimap< _Key, _Tp, _H2, _P2, _Alloc > &&__source) template void merge (unordered_multimap< _Key, _Tp, _H2, _P2, _Alloc > &__source) unordered_map & operator= (const unordered_map &)=default Copy assignment operator. unordered_map & operator= (initializer_list< value_type > __l) Unordered_map list assignment operator. unordered_map & operator= (unordered_map &&)=default Move assignment operator. void rehash (size_type __n) May rehash the unordered_map. void reserve (size_type __n) Prepare the unordered_map for a specified number of elements. size_type size () const noexcept Returns the size of the unordered_map. void swap (unordered_map &__x) noexcept(noexcept(_M_h.swap(__x._M_h))) Swaps data with another unordered_map. template pair< iterator, bool > try_emplace (const key_type &__k, _Args &&... __args) Attempts to build and insert a std::pair into the unordered_map. template iterator try_emplace (const_iterator __hint, const key_type &__k, _Args &&... __args) Attempts to build and insert a std::pair into the unordered_map. template iterator try_emplace (const_iterator __hint, key_type &&__k, _Args &&... __args) template pair< iterator, bool > try_emplace (key_type &&__k, _Args &&... __args) const_iterator begin () const noexcept const_iterator cbegin () const noexcept const_iterator end () const noexcept const_iterator cend () const noexcept std::pair< iterator, bool > insert (const value_type &__x) Attempts to insert a std::pair into the unordered_map. std::pair< iterator, bool > insert (value_type &&__x) Attempts to insert a std::pair into the unordered_map. template __enable_if_t< is_constructible< value_type, _Pair && >::value, pair< iterator, bool > > insert (_Pair &&__x) Attempts to insert a std::pair into the unordered_map. iterator insert (const_iterator __hint, const value_type &__x) Attempts to insert a std::pair into the unordered_map. iterator insert (const_iterator __hint, value_type &&__x) Attempts to insert a std::pair into the unordered_map. template __enable_if_t< is_constructible< value_type, _Pair && >::value, iterator > insert (const_iterator __hint, _Pair &&__x) Attempts to insert a std::pair into the unordered_map. iterator erase (const_iterator __position) Erases an element from an unordered_map. iterator erase (iterator __position) Erases an element from an unordered_map. iterator find (const key_type &__x) Tries to locate an element in an unordered_map. template auto find (const _Kt &__x) -> decltype(_M_h._M_find_tr(__x)) Tries to locate an element in an unordered_map. const_iterator find (const key_type &__x) const Tries to locate an element in an unordered_map. template auto find (const _Kt &__x) const -> decltype(_M_h._M_find_tr(__x)) Tries to locate an element in an unordered_map. size_type count (const key_type &__x) const Finds the number of elements. template auto count (const _Kt &__x) const -> decltype(_M_h._M_count_tr(__x)) Finds the number of elements. bool contains (const key_type &__x) const Finds whether an element with the given key exists. template auto contains (const _Kt &__x) const -> decltype(_M_h._M_find_tr(__x), void(), true) Finds whether an element with the given key exists. std::pair< iterator, iterator > equal_range (const key_type &__x) Finds a subsequence matching given key. template auto equal_range (const _Kt &__x) -> decltype(_M_h._M_equal_range_tr(__x)) Finds a subsequence matching given key. std::pair< const_iterator, const_iterator > equal_range (const key_type &__x) const Finds a subsequence matching given key. template auto equal_range (const _Kt &__x) const -> decltype(_M_h._M_equal_range_tr(__x)) Finds a subsequence matching given key. mapped_type & operator[] (const key_type &__k) Subscript ( [] ) access to unordered_map data. mapped_type & operator[] (key_type &&__k) Subscript ( [] ) access to unordered_map data. mapped_type & at (const key_type &__k) Access to unordered_map data. const mapped_type & at (const key_type &__k) const Access to unordered_map data. const_local_iterator begin (size_type __n) const Returns a read-only (constant) iterator pointing to the first bucket element. const_local_iterator cbegin (size_type __n) const Returns a read-only (constant) iterator pointing to the first bucket element. const_local_iterator end (size_type __n) const Returns a read-only (constant) iterator pointing to one past the last bucket elements. const_local_iterator cend (size_type __n) const Returns a read-only (constant) iterator pointing to one past the last bucket elements. Friends template bool operator== (const unordered_map< _Key1, _Tp1, _Hash1, _Pred1, _Alloc1 > &, const unordered_map< _Key1, _Tp1, _Hash1, _Pred1, _Alloc1 > &) template class std::_Hash_merge_helper Detailed Description template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> class std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >"A standard container composed of unique keys (containing at most one of each key value) that associates values of another type with the keys. Since C++11 Template Parameters _Key Type of key objects. _Tp Type of mapped objects. _Hash Hashing function object type, defaults to hash<_Value>. _Pred Predicate function object type, defaults to equal_to<_Value>. _Alloc Allocator type, defaults to std::allocator>. Meets the requirements of a container, and unordered associative container The resulting value type of the container is std::pair. Base is _Hashtable, dispatched at compile time via template alias __umap_hashtable. Member Typedef Documentation template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::allocator_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::allocator_type Public typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::const_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::const_iterator Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::const_local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::const_local_iterator Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::const_pointer std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::const_pointer Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::const_reference std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::const_reference Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::difference_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::difference_type Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::hasher std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::hasher Public typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::iterator Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::key_equal std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::key_equal Public typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::key_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::key_type Public typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::local_iterator Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::mapped_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::mapped_type Public typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::pointer std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::pointer Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::reference std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::reference Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::size_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::size_type Iterator-related typedefs. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> typedef _Hashtable::value_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::value_type Public typedefs. Constructor & Destructor Documentation template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_map () [default] Default constructor. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_map (size_type __n, const hasher & __hf = hasher(), const key_equal & __eql = key_equal(), const allocator_type & __a = allocator_type()) [inline], [explicit] Default constructor creates no elements. Parameters __n Minimal initial number of buckets. __hf A hash functor. __eql A key equality functor. __a An allocator object. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_map (_InputIterator __first, _InputIterator __last, size_type __n = 0, const hasher & __hf = hasher(), const key_equal & __eql = key_equal(), const allocator_type & __a = allocator_type()) [inline] Builds an unordered_map from a range. Parameters __first An input iterator. __last An input iterator. __n Minimal initial number of buckets. __hf A hash functor. __eql A key equality functor. __a An allocator object. Create an unordered_map consisting of copies of the elements from [__first,__last). This is linear in N (where N is distance(__first,__last)). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_map (const unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc > &) [default] Copy constructor. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_map (unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc > &&) [default] Move constructor. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_map (const allocator_type & __a) [inline], [explicit] Creates an unordered_map with no elements. Parameters __a An allocator object. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_map (initializer_list< value_type > __l, size_type __n = 0, const hasher & __hf = hasher(), const key_equal & __eql = key_equal(), const allocator_type & __a = allocator_type()) [inline] Builds an unordered_map from an initializer_list. Parameters __l An initializer_list. __n Minimal initial number of buckets. __hf A hash functor. __eql A key equality functor. __a An allocator object. Create an unordered_map consisting of copies of the elements in the list. This is linear in N (where N is __l.size()). Member Function Documentation template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> mapped_type & std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::at (const key_type & __k) [inline] Access to unordered_map data. Parameters __k The key for which data should be retrieved. Returns A reference to the data whose key is equal to __k, if such a data is present in the unordered_map. Exceptions std::out_of_range If no such data is present. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const mapped_type & std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::at (const key_type & __k) const [inline] Access to unordered_map data. Parameters __k The key for which data should be retrieved. Returns A reference to the data whose key is equal to __k, if such a data is present in the unordered_map. Exceptions std::out_of_range If no such data is present. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::begin () const [inline], [noexcept] Returns a read-only (constant) iterator that points to the first element in the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::begin () [inline], [noexcept] Returns a read/write iterator that points to the first element in the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::begin (size_type __n) [inline] Returns a read/write iterator pointing to the first bucket element. Parameters __n The bucket index. Returns A read/write local iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::begin (size_type __n) const [inline] Returns a read-only (constant) iterator pointing to the first bucket element. Parameters __n The bucket index. Returns A read-only local iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> size_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::bucket_count () const [inline], [noexcept] Returns the number of buckets of the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::cbegin () const [inline], [noexcept] Returns a read-only (constant) iterator that points to the first element in the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::cbegin (size_type __n) const [inline] Returns a read-only (constant) iterator pointing to the first bucket element. Parameters __n The bucket index. Returns A read-only local iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::cend () const [inline], [noexcept] Returns a read-only (constant) iterator that points one past the last element in the unordered_map. Referenced by std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert_or_assign(), and std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::try_emplace(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::cend (size_type __n) const [inline] Returns a read-only (constant) iterator pointing to one past the last bucket elements. Parameters __n The bucket index. Returns A read-only local iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> void std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::clear () [inline], [noexcept] Erases all elements in an unordered_map. Note that this function only erases the elements, and that if the elements themselves are pointers, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template auto std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::contains (const _Kt & __x) const -> decltype(_M_h._M_find_tr(__x), void(), true) [inline]" Finds whether an element with the given key exists. Parameters __x Key of elements to be located. Returns True if there is any element with the specified key. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> bool std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::contains (const key_type & __x) const [inline] Finds whether an element with the given key exists. Parameters __x Key of elements to be located. Returns True if there is any element with the specified key. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template auto std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::count (const _Kt & __x) const -> decltype(_M_h._M_count_tr(__x)) [inline]" Finds the number of elements. Parameters __x Key to count. Returns Number of elements with specified key. This function only makes sense for unordered_multimap; for unordered_map the result will either be 0 (not present) or 1 (present). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> size_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::count (const key_type & __x) const [inline] Finds the number of elements. Parameters __x Key to count. Returns Number of elements with specified key. This function only makes sense for unordered_multimap; for unordered_map the result will either be 0 (not present) or 1 (present). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template std::pair< iterator, bool > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::emplace (_Args &&... __args) [inline] Attempts to build and insert a std::pair into the unordered_map. Parameters __args Arguments used to generate a new pair instance (see std::piecewise_contruct for passing arguments to each part of the pair constructor). Returns A pair, of which the first element is an iterator that points to the possibly inserted pair, and the second is a bool that is true if the pair was actually inserted. This function attempts to build and insert a (key, value) pair into the unordered_map. An unordered_map relies on unique keys and thus a pair is only inserted if its first element (the key) is not already present in the unordered_map. Insertion requires amortized constant time. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::emplace_hint (const_iterator __pos, _Args &&... __args) [inline] Attempts to build and insert a std::pair into the unordered_map. Parameters __pos An iterator that serves as a hint as to where the pair should be inserted. __args Arguments used to generate a new pair instance (see std::piecewise_contruct for passing arguments to each part of the pair constructor). Returns An iterator that points to the element with key of the std::pair built from __args (may or may not be that std::pair). This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument emplace() does. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints for more on hinting. Insertion requires amortized constant time. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> bool std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::empty () const [inline], [noexcept] Returns true if the unordered_map is empty. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::end () const [inline], [noexcept] Returns a read-only (constant) iterator that points one past the last element in the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::end () [inline], [noexcept] Returns a read/write iterator that points one past the last element in the unordered_map. Referenced by std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::extract(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::end (size_type __n) [inline] Returns a read/write iterator pointing to one past the last bucket elements. Parameters __n The bucket index. Returns A read/write local iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_local_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::end (size_type __n) const [inline] Returns a read-only (constant) iterator pointing to one past the last bucket elements. Parameters __n The bucket index. Returns A read-only local iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template auto std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::equal_range (const _Kt & __x) -> decltype(_M_h._M_equal_range_tr(__x)) [inline]" Finds a subsequence matching given key. Parameters __x Key to be located. Returns Pair of iterators that possibly points to the subsequence matching given key. This function probably only makes sense for unordered_multimap. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template auto std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::equal_range (const _Kt & __x) const -> decltype(_M_h._M_equal_range_tr(__x)) [inline]" Finds a subsequence matching given key. Parameters __x Key to be located. Returns Pair of iterators that possibly points to the subsequence matching given key. This function probably only makes sense for unordered_multimap. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::pair< iterator, iterator > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::equal_range (const key_type & __x) [inline] Finds a subsequence matching given key. Parameters __x Key to be located. Returns Pair of iterators that possibly points to the subsequence matching given key. This function probably only makes sense for unordered_multimap. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::pair< const_iterator, const_iterator > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::equal_range (const key_type & __x) const [inline] Finds a subsequence matching given key. Parameters __x Key to be located. Returns Pair of iterators that possibly points to the subsequence matching given key. This function probably only makes sense for unordered_multimap. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> size_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::erase (const key_type & __x) [inline] Erases elements according to the provided key. Parameters __x Key of element to be erased. Returns The number of elements erased. This function erases all the elements located by the given key from an unordered_map. For an unordered_map the result of this function can only be 0 (not present) or 1 (present). Note that this function only erases the element, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::erase (const_iterator __first, const_iterator __last) [inline] Erases a [__first,__last) range of elements from an unordered_map. Parameters __first Iterator pointing to the start of the range to be erased. __last Iterator pointing to the end of the range to be erased. Returns The iterator __last. This function erases a sequence of elements from an unordered_map. Note that this function only erases the elements, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::erase (const_iterator __position) [inline] Erases an element from an unordered_map. Parameters __position An iterator pointing to the element to be erased. Returns An iterator pointing to the element immediately following __position prior to the element being erased. If no such element exists, end() is returned. This function erases an element, pointed to by the given iterator, from an unordered_map. Note that this function only erases the element, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::erase (iterator __position) [inline] Erases an element from an unordered_map. Parameters __position An iterator pointing to the element to be erased. Returns An iterator pointing to the element immediately following __position prior to the element being erased. If no such element exists, end() is returned. This function erases an element, pointed to by the given iterator, from an unordered_map. Note that this function only erases the element, and that if the element is itself a pointer, the pointed-to memory is not touched in any way. Managing the pointer is the user's responsibility. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> node_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::extract (const key_type & __key) [inline] Extract a node. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> node_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::extract (const_iterator __pos) [inline] Extract a node. References std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::end(), and std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template auto std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::find (const _Kt & __x) -> decltype(_M_h._M_find_tr(__x)) [inline]" Tries to locate an element in an unordered_map. Parameters __x Key to be located. Returns Iterator pointing to sought-after element, or end() if not found. This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template auto std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::find (const _Kt & __x) const -> decltype(_M_h._M_find_tr(__x)) [inline]" Tries to locate an element in an unordered_map. Parameters __x Key to be located. Returns Iterator pointing to sought-after element, or end() if not found. This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::find (const key_type & __x) [inline] Tries to locate an element in an unordered_map. Parameters __x Key to be located. Returns Iterator pointing to sought-after element, or end() if not found. This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> const_iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::find (const key_type & __x) const [inline] Tries to locate an element in an unordered_map. Parameters __x Key to be located. Returns Iterator pointing to sought-after element, or end() if not found. This function takes a key and tries to locate the element with which the key matches. If successful the function returns an iterator pointing to the sought after element. If unsuccessful it returns the past-the-end ( end() ) iterator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> allocator_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::get_allocator () const [inline], [noexcept] Returns the allocator object used by the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> hasher std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::hash_function () const [inline] Returns the hash functor object with which the unordered_map was constructed. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template void std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (_InputIterator __first, _InputIterator __last) [inline] A template function that attempts to insert a range of elements. Parameters __first Iterator pointing to the start of the range to be inserted. __last Iterator pointing to the end of the range. Complexity similar to that of the range constructor. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template __enable_if_t< is_constructible< value_type, _Pair && >::value, pair< iterator, bool > > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (_Pair && __x) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __x Pair to be inserted (see std::make_pair for easy creation of pairs). Returns A pair, of which the first element is an iterator that points to the possibly inserted pair, and the second is a bool that is true if the pair was actually inserted. This function attempts to insert a (key, value) pair into the unordered_map. An unordered_map relies on unique keys and thus a pair is only inserted if its first element (the key) is not already present in the unordered_map. Insertion requires amortized constant time. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::pair< iterator, bool > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (const value_type & __x) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __x Pair to be inserted (see std::make_pair for easy creation of pairs). Returns A pair, of which the first element is an iterator that points to the possibly inserted pair, and the second is a bool that is true if the pair was actually inserted. This function attempts to insert a (key, value) pair into the unordered_map. An unordered_map relies on unique keys and thus a pair is only inserted if its first element (the key) is not already present in the unordered_map. Insertion requires amortized constant time. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template __enable_if_t< is_constructible< value_type, _Pair && >::value, iterator > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (const_iterator __hint, _Pair && __x) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __hint An iterator that serves as a hint as to where the pair should be inserted. __x Pair to be inserted (see std::make_pair for easy creation of pairs). Returns An iterator that points to the element with key of __x (may or may not be the pair passed in). This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument insert() does. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints for more on hinting. Insertion requires amortized constant time. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (const_iterator __hint, const value_type & __x) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __hint An iterator that serves as a hint as to where the pair should be inserted. __x Pair to be inserted (see std::make_pair for easy creation of pairs). Returns An iterator that points to the element with key of __x (may or may not be the pair passed in). This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument insert() does. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints for more on hinting. Insertion requires amortized constant time. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (const_iterator __hint, value_type && __x) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __hint An iterator that serves as a hint as to where the pair should be inserted. __x Pair to be inserted (see std::make_pair for easy creation of pairs). Returns An iterator that points to the element with key of __x (may or may not be the pair passed in). This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument insert() does. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints for more on hinting. Insertion requires amortized constant time. References std::forward(), and std::move(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (const_iterator, node_type && __nh) [inline] Re-insert an extracted node. References std::forward(), and std::move(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> void std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (initializer_list< value_type > __l) [inline] Attempts to insert a list of elements into the unordered_map. Parameters __l A std::initializer_list of elements to be inserted. Complexity similar to that of the range constructor. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> insert_return_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (node_type && __nh) [inline] Re-insert an extracted node. References std::forward(), and std::move(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> std::pair< iterator, bool > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert (value_type && __x) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __x Pair to be inserted (see std::make_pair for easy creation of pairs). Returns A pair, of which the first element is an iterator that points to the possibly inserted pair, and the second is a bool that is true if the pair was actually inserted. This function attempts to insert a (key, value) pair into the unordered_map. An unordered_map relies on unique keys and thus a pair is only inserted if its first element (the key) is not already present in the unordered_map. Insertion requires amortized constant time. References std::move(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template pair< iterator, bool > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert_or_assign (const key_type & __k, _Obj && __obj) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __k Key to use for finding a possibly existing pair in the map. __obj Argument used to generate the .second for a pair instance. Returns A pair, of which the first element is an iterator that points to the possibly inserted pair, and the second is a bool that is true if the pair was actually inserted. This function attempts to insert a (key, value) pair into the unordered_map. An unordered_map relies on unique keys and thus a pair is only inserted if its first element (the key) is not already present in the unordered_map. If the pair was already in the unordered_map, the .second of the pair is assigned from __obj. Insertion requires amortized constant time. References std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::cend(), and std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::insert_or_assign (const_iterator __hint, const key_type & __k, _Obj && __obj) [inline] Attempts to insert a std::pair into the unordered_map. Parameters __hint An iterator that serves as a hint as to where the pair should be inserted. __k Key to use for finding a possibly existing pair in the unordered_map. __obj Argument used to generate the .second for a pair instance. Returns An iterator that points to the element with key of __x (may or may not be the pair passed in). This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument insert() does. If the pair was already in the unordered map, the .second of the pair is assigned from __obj. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints for more on hinting. Insertion requires amortized constant time. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> key_equal std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::key_eq () const [inline] Returns the key comparison object with which the unordered_map was constructed. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> float std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::load_factor () const [inline], [noexcept] Returns the average number of elements per bucket. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> size_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::max_bucket_count () const [inline], [noexcept] Returns the maximum number of buckets of the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> float std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::max_load_factor () const [inline], [noexcept] Returns a positive number that the unordered_map tries to keep the load factor less than or equal to. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> void std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::max_load_factor (float __z) [inline] Change the unordered_map maximum load factor. Parameters __z The new maximum load factor. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> size_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::max_size () const [inline], [noexcept] Returns the maximum size of the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> unordered_map & std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::operator= (const unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc > &) [default] Copy assignment operator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> unordered_map & std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::operator= (initializer_list< value_type > __l) [inline] Unordered_map list assignment operator. Parameters __l An initializer_list. This function fills an unordered_map with copies of the elements in the initializer list __l. Note that the assignment completely changes the unordered_map and that the resulting unordered_map's size is the same as the number of elements assigned. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> unordered_map & std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::operator= (unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc > &&) [default] Move assignment operator. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> mapped_type & std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::operator[] (const key_type & __k) [inline] Subscript ( [] ) access to unordered_map data. Parameters __k The key for which data should be retrieved. Returns A reference to the data of the (key,data) pair. Allows for easy lookup with the subscript ( [] )operator. Returns data associated with the key specified in subscript. If the key does not exist, a pair with that key is created using default values, which is then returned. Lookup requires constant time. References std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> mapped_type & std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::operator[] (key_type && __k) [inline] Subscript ( [] ) access to unordered_map data. Parameters __k The key for which data should be retrieved. Returns A reference to the data of the (key,data) pair. Allows for easy lookup with the subscript ( [] )operator. Returns data associated with the key specified in subscript. If the key does not exist, a pair with that key is created using default values, which is then returned. Lookup requires constant time. References std::forward(), and std::move(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> void std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::rehash (size_type __n) [inline] May rehash the unordered_map. Parameters __n The new number of buckets. Rehash will occur only if the new number of buckets respect the unordered_map maximum load factor. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> void std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::reserve (size_type __n) [inline] Prepare the unordered_map for a specified number of elements. Parameters __n Number of elements required. Same as rehash(ceil(n / max_load_factor())). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> size_type std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::size () const [inline], [noexcept] Returns the size of the unordered_map. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> void std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::swap (unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc > & __x) [inline], [noexcept] Swaps data with another unordered_map. Parameters __x An unordered_map of the same element and allocator types. This exchanges the elements between two unordered_map in constant time. Note that the global std::swap() function is specialized such that std::swap(m1,m2) will feed to this function. template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template pair< iterator, bool > std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::try_emplace (const key_type & __k, _Args &&... __args) [inline] Attempts to build and insert a std::pair into the unordered_map. Parameters __k Key to use for finding a possibly existing pair in the unordered_map. __args Arguments used to generate the .second for a new pair instance. Returns A pair, of which the first element is an iterator that points to the possibly inserted pair, and the second is a bool that is true if the pair was actually inserted. This function attempts to build and insert a (key, value) pair into the unordered_map. An unordered_map relies on unique keys and thus a pair is only inserted if its first element (the key) is not already present in the unordered_map. If a pair is not inserted, this function has no effect. Insertion requires amortized constant time. References std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::cend(), and std::forward(). template, typename _Pred = equal_to<_Key>, typename _Alloc = allocator>> template iterator std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >::try_emplace (const_iterator __hint, const key_type & __k, _Args &&... __args) [inline] Attempts to build and insert a std::pair into the unordered_map. Parameters __hint An iterator that serves as a hint as to where the pair should be inserted. __k Key to use for finding a possibly existing pair in the unordered_map. __args Arguments used to generate the .second for a new pair instance. Returns An iterator that points to the element with key of the std::pair built from __args (may or may not be that std::pair). This function is not concerned about whether the insertion took place, and thus does not return a boolean like the single-argument emplace() does. However, if insertion did not take place, this function has no effect. Note that the first parameter is only a hint and can potentially improve the performance of the insertion process. A bad hint would cause no gains in efficiency. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/associative.html#containers.associative.insert_hints for more on hinting. Insertion requires amortized constant time. References std::forward(). Author Generated automatically by Doxygen for libstdc++ from the source code. libstdc++ std::unordered_map< _Key, _Tp, _Hash, _Pred, _Alloc >(3)