std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc > Class Template Reference
Containers » Unordered Associative

## Public Types

typedef _Hashtable::key_type | key_type
typedef _Hashtable::value_type | value_type
typedef _Hashtable::mapped_type | mapped_type
typedef _Hashtable::hasher | hasher
typedef _Hashtable::key_equal | key_equal
typedef _Hashtable::allocator_type | allocator_type
typedef _Hashtable::pointer | pointer
typedef _Hashtable::const_pointer | const_pointer
typedef _Hashtable::reference | reference
typedef _Hashtable::const_reference | const_reference
typedef _Hashtable::iterator | iterator
typedef _Hashtable::const_iterator | const_iterator
typedef _Hashtable::local_iterator | local_iterator
typedef _Hashtable::const_local_iterator | const_local_iterator
typedef _Hashtable::size_type | size_type
typedef _Hashtable::difference_type | difference_type

## Public Member Functions

| unordered_multimap ()=default
| unordered_multimap (size_type __n, const hasher &__hf=hasher(), const key_equal &__eql=key_equal(), const allocator_type &__a=allocator_type())
template<typename _InputIterator >
| unordered_multimap (_InputIterator __first, _InputIterator __last, size_type __n=0, const hasher &__hf=hasher(), const key_equal &__eql=key_equal(), const allocator_type &__a=allocator_type())
| unordered_multimap (const unordered_multimap &)=default
| unordered_multimap (unordered_multimap &&)=default
| unordered_multimap (const allocator_type &__a)
| unordered_multimap (const unordered_multimap &__ummap, const allocator_type &__a)
| unordered_multimap (unordered_multimap &&__ummap, const allocator_type &__a)
| unordered_multimap (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())
| unordered_multimap (size_type __n, const allocator_type &__a)
| unordered_multimap (size_type __n, const hasher &__hf, const allocator_type &__a)
template<typename _InputIterator >
| unordered_multimap (_InputIterator __first, _InputIterator __last, size_type __n, const allocator_type &__a)
template<typename _InputIterator >
| unordered_multimap (_InputIterator __first, _InputIterator __last, size_type __n, const hasher &__hf, const allocator_type &__a)
| unordered_multimap (initializer_list< value_type > __l, size_type __n, const allocator_type &__a)
| unordered_multimap (initializer_list< value_type > __l, size_type __n, const hasher &__hf, const allocator_type &__a)
iterator | begin () noexcept
local_iterator | begin (size_type __n)
size_type | bucket (const key_type &__key) const
size_type | bucket_count () const noexcept
size_type | bucket_size (size_type __n) const
void | clear () noexcept
size_type | count (const key_type &__x) const
template<typename... _Args>
iterator | emplace (_Args &&... __args)
template<typename... _Args>
iterator | emplace_hint (const_iterator __pos, _Args &&... __args)
bool | empty () const noexcept
iterator | end () noexcept
local_iterator | end (size_type __n)
size_type | erase (const key_type &__x)
iterator | erase (const_iterator __first, const_iterator __last)
allocator_type | get_allocator () const noexcept
hasher | hash_function () const
template<typename _InputIterator >
void | insert (_InputIterator __first, _InputIterator __last)
void | insert (initializer_list< value_type > __l)
key_equal | key_eq () const
float | load_factor () const noexcept
size_type | max_bucket_count () const noexcept
float | max_load_factor () const noexcept
void | max_load_factor (float __z)
size_type | max_size () const noexcept
unordered_multimap & | operator= (const unordered_multimap &)=default
unordered_multimap & | operator= (unordered_multimap &&)=default
unordered_multimap & | operator= (initializer_list< value_type > __l)
void | rehash (size_type __n)
void | reserve (size_type __n)
size_type | size () const noexcept
void | swap (unordered_multimap &__x) noexcept(noexcept(_M_h.swap(__x._M_h)))
const_iterator | begin () const noexcept
const_iterator | cbegin () const noexcept
const_iterator | end () const noexcept
const_iterator | cend () const noexcept
iterator | insert (const value_type &__x)
iterator | insert (value_type &&__x)
template<typename _Pair , typename = typename std::enable_if<std::is_constructible<value_type, _Pair&&>::value>::type>
iterator | insert (_Pair &&__x)
iterator | insert (const_iterator __hint, const value_type &__x)
iterator | insert (const_iterator __hint, value_type &&__x)
template<typename _Pair , typename = typename std::enable_if<std::is_constructible<value_type, _Pair&&>::value>::type>
iterator | insert (const_iterator __hint, _Pair &&__x)
iterator | erase (const_iterator __position)
iterator | erase (iterator __position)
iterator | find (const key_type &__x)
const_iterator | find (const key_type &__x) const
std::pair< iterator, iterator > | equal_range (const key_type &__x)
std::pair< const_iterator, const_iterator > | equal_range (const key_type &__x) const
const_local_iterator | begin (size_type __n) const
const_local_iterator | cbegin (size_type __n) const
const_local_iterator | end (size_type __n) const
const_local_iterator | cend (size_type __n) const

## Friends

template<typename _Key1 , typename _Tp1 , typename _Hash1 , typename _Pred1 , typename _Alloc1 >
bool | operator== (const unordered_multimap< _Key1, _Tp1, _Hash1, _Pred1, _Alloc1 > &, const unordered_multimap< _Key1, _Tp1, _Hash1, _Pred1, _Alloc1 > &)

## Detailed Description

### template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
class std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >

A standard container composed of equivalent keys (possibly containing multiple of each key value) that associates values of another type with the keys.

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<std::pair<const _Key, _Tp>>.

Meets the requirements of a container, and unordered associative container

The resulting value type of the container is std::pair<const _Key, _Tp>.

Base is _Hashtable, dispatched at compile time via template alias __ummap_hashtable.

Definition at line 73 of file unordered_map.h.

## Member Typedef Documentation

## allocator_type

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::allocator_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::allocator_type

Public typedefs.

Definition at line 1250 of file unordered_map.h.

## const_iterator

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::const_iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::const_iterator

Iterator-related typedefs.

Definition at line 1260 of file unordered_map.h.

## const_local_iterator

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::const_local_iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::const_local_iterator

Iterator-related typedefs.

Definition at line 1262 of file unordered_map.h.

## const_pointer

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::const_pointer std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::const_pointer

Iterator-related typedefs.

Definition at line 1256 of file unordered_map.h.

## const_reference

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::const_reference std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::const_reference

Iterator-related typedefs.

Definition at line 1258 of file unordered_map.h.

## difference_type

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::difference_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::difference_type

Iterator-related typedefs.

Definition at line 1264 of file unordered_map.h.

## hasher

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::hasher std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::hasher

Public typedefs.

Definition at line 1248 of file unordered_map.h.

## iterator

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::iterator

Iterator-related typedefs.

Definition at line 1259 of file unordered_map.h.

## key_equal

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::key_equal std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::key_equal

Public typedefs.

Definition at line 1249 of file unordered_map.h.

## key_type

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::key_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::key_type

Public typedefs.

Definition at line 1245 of file unordered_map.h.

## local_iterator

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::local_iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::local_iterator

Iterator-related typedefs.

Definition at line 1261 of file unordered_map.h.

## mapped_type

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::mapped_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::mapped_type

Public typedefs.

Definition at line 1247 of file unordered_map.h.

## pointer

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::pointer std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::pointer

Iterator-related typedefs.

Definition at line 1255 of file unordered_map.h.

## reference

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::reference std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::reference

Iterator-related typedefs.

Definition at line 1257 of file unordered_map.h.

## size_type

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::size_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::size_type

Iterator-related typedefs.

Definition at line 1263 of file unordered_map.h.

## value_type

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

typedef _Hashtable::value_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::value_type

Public typedefs.

Definition at line 1246 of file unordered_map.h.

## Constructor & Destructor Documentation

## unordered_multimap() [1/7]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_multimap | ( |  | ) |

default

Default constructor.

## unordered_multimap() [2/7]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_multimap | ( | 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 | Mnimal initial number of buckets.
  __hf | A hash functor.
  __eql | A key equality functor.
  __a | An allocator object.

Definition at line 1284 of file unordered_map.h.

## unordered_multimap() [3/7]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
template<typename _InputIterator >

std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_multimap | ( | _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_multimap 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_multimap consisting of copies of the elements from [__first,__last). This is linear in N (where N is distance(__first,__last)).

Definition at line 1305 of file unordered_map.h.

## unordered_multimap() [4/7]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_multimap | ( | const unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc > & |  | ) |

default

Copy constructor.

## unordered_multimap() [5/7]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_multimap | ( | unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc > && |  | ) |

default

Move constructor.

## unordered_multimap() [6/7]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_multimap | ( | const allocator_type & | __a | ) |

inline explicit

Creates an unordered_multimap with no elements.

Parameters

  __a | An allocator object.

Definition at line 1324 of file unordered_map.h.

## unordered_multimap() [7/7]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::unordered_multimap | ( | 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_multimap 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_multimap consisting of copies of the elements in the list. This is linear in N (where N is __l.size()).

Definition at line 1359 of file unordered_map.h.

## Member Function Documentation

## begin() [1/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::begin | ( |  | ) |

inline noexcept

Returns a read/write iterator that points to the first element in the unordered_multimap.

Definition at line 1457 of file unordered_map.h.

## begin() [2/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::begin | ( |  | ) | const

inline noexcept

Returns a read-only (constant) iterator that points to the first element in the unordered_multimap.

Definition at line 1466 of file unordered_map.h.

## begin() [3/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

local_iterator std::unordered_multimap< _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.

Definition at line 1875 of file unordered_map.h.

## begin() [4/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_local_iterator std::unordered_multimap< _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.

Definition at line 1886 of file unordered_map.h.

## bucket_count()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

size_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::bucket_count | ( |  | ) | const

inline noexcept

Returns the number of buckets of the unordered_multimap.

Definition at line 1842 of file unordered_map.h.

## cbegin() [1/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::cbegin | ( |  | ) | const

inline noexcept

Returns a read-only (constant) iterator that points to the first element in the unordered_multimap.

Definition at line 1470 of file unordered_map.h.

## cbegin() [2/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_local_iterator std::unordered_multimap< _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.

Definition at line 1890 of file unordered_map.h.

## cend() [1/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_iterator std::unordered_multimap< _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_multimap.

Definition at line 1492 of file unordered_map.h.

## cend() [2/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_local_iterator std::unordered_multimap< _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.

Definition at line 1916 of file unordered_map.h.

## clear()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

void std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::clear | ( |  | ) |

inline noexcept

Erases all elements in an unordered_multimap. 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.

Definition at line 1725 of file unordered_map.h.

## count()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

size_type std::unordered_multimap< _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.

Definition at line 1819 of file unordered_map.h.

## emplace()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
template<typename... _Args>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::emplace | ( | _Args &&... | __args | ) |

inline

Attempts to build and insert a std::pair into the unordered_multimap.

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
  An iterator that points to the inserted pair.

This function attempts to build and insert a (key, value) pair into the unordered_multimap.

Insertion requires amortized constant time.

Definition at line 1515 of file unordered_map.h.

## emplace_hint()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
template<typename... _Args>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::emplace_hint | ( | const_iterator | __pos,
|  | _Args &&... | __args
| ) |  |

inline

Attempts to build and insert a std::pair into the unordered_multimap.

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.

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.

Definition at line 1542 of file unordered_map.h.

## empty()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

bool std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::empty | ( |  | ) | const

inline noexcept

Returns true if the unordered_multimap is empty.

Definition at line 1437 of file unordered_map.h.

## end() [1/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::end | ( |  | ) |

inline noexcept

Returns a read/write iterator that points one past the last element in the unordered_multimap.

Definition at line 1479 of file unordered_map.h.

## end() [2/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_iterator std::unordered_multimap< _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_multimap.

Definition at line 1488 of file unordered_map.h.

## end() [3/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

local_iterator std::unordered_multimap< _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.

Definition at line 1901 of file unordered_map.h.

## end() [4/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_local_iterator std::unordered_multimap< _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.

Definition at line 1912 of file unordered_map.h.

## equal_range() [1/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::pair<iterator, iterator> std::unordered_multimap< _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.

Definition at line 1830 of file unordered_map.h.

## equal_range() [2/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

std::pair<const_iterator, const_iterator> std::unordered_multimap< _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.

Definition at line 1834 of file unordered_map.h.

## erase() [1/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::erase | ( | const_iterator | __position | ) |

inline

Erases an element from an unordered_multimap.

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_multimap. 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.

Definition at line 1675 of file unordered_map.h.

## erase() [2/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::erase | ( | iterator | __position | ) |

inline

Erases an element from an unordered_multimap.

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_multimap. 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.

Definition at line 1680 of file unordered_map.h.

## erase() [3/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

size_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::erase | ( | const key_type & | __x | ) |

inline

Erases elements according to the provided key.

Parameters

  __x | Key of elements to be erased.

Returns
  The number of elements erased.

This function erases all the elements located by the given key from an unordered_multimap. 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.

Definition at line 1696 of file unordered_map.h.

## erase() [4/4]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::erase | ( | const_iterator | __first,
|  | const_iterator | __last
| ) |  |

inline

Erases a [__first,__last) range of elements from an unordered_multimap.

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_multimap. 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.

Definition at line 1715 of file unordered_map.h.

## find() [1/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::find | ( | const key_type & | __x | ) |

inline

Tries to locate an element in an unordered_multimap.

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.

Definition at line 1805 of file unordered_map.h.

## find() [2/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

const_iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::find | ( | const key_type & | __x | ) | const

inline

Tries to locate an element in an unordered_multimap.

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.

Definition at line 1809 of file unordered_map.h.

## get_allocator()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

allocator_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::get_allocator | ( |  | ) | const

inline noexcept

Returns the allocator object used by the unordered_multimap.

Definition at line 1430 of file unordered_map.h.

## hash_function()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

hasher std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::hash_function | ( |  | ) | const

inline

Returns the hash functor object with which the unordered_multimap was constructed.

Definition at line 1781 of file unordered_map.h.

## insert() [1/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::insert | ( | const value_type & | __x | ) |

inline

Inserts a std::pair into the unordered_multimap.

Parameters

  __x | Pair to be inserted (see std::make_pair for easy creation of pairs).

Returns
  An iterator that points to the inserted pair.

Insertion requires amortized constant time.

Definition at line 1556 of file unordered_map.h.

## insert() [2/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::insert | ( | value_type && | __x | ) |

inline

Inserts a std::pair into the unordered_multimap.

Parameters

  __x | Pair to be inserted (see std::make_pair for easy creation of pairs).

Returns
  An iterator that points to the inserted pair.

Insertion requires amortized constant time.

Definition at line 1560 of file unordered_map.h.

## insert() [3/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
template<typename _Pair , typename = typename std::enable_if<std::is_constructible<value_type, _Pair&&>::value>::type>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::insert | ( | _Pair && | __x | ) |

inline

Inserts a std::pair into the unordered_multimap.

Parameters

  __x | Pair to be inserted (see std::make_pair for easy creation of pairs).

Returns
  An iterator that points to the inserted pair.

Insertion requires amortized constant time.

Definition at line 1567 of file unordered_map.h.

## insert() [4/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::insert | ( | const_iterator | __hint,
|  | const value_type & | __x
| ) |  |

inline

Inserts a std::pair into the unordered_multimap.

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).

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.

Definition at line 1592 of file unordered_map.h.

## insert() [5/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::insert | ( | const_iterator | __hint,
|  | value_type && | __x
| ) |  |

inline

Inserts a std::pair into the unordered_multimap.

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).

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.

Definition at line 1598 of file unordered_map.h.

## insert() [6/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
template<typename _Pair , typename = typename std::enable_if<std::is_constructible<value_type, _Pair&&>::value>::type>

iterator std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::insert | ( | const_iterator | __hint,
|  | _Pair && | __x
| ) |  |

inline

Inserts a std::pair into the unordered_multimap.

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).

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.

Definition at line 1605 of file unordered_map.h.

## insert() [7/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>
template<typename _InputIterator >

void std::unordered_multimap< _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.

Definition at line 1620 of file unordered_map.h.

## insert() [8/8]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

void std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::insert | ( | initializer_list< value_type > | __l | ) |

inline

Attempts to insert a list of elements into the unordered_multimap.

Parameters

  __l | A std::initializer_list<value_type> of elements to be inserted.

Complexity similar to that of the range constructor.

Definition at line 1632 of file unordered_map.h.

## key_eq()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

key_equal std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::key_eq | ( |  | ) | const

inline

Returns the key comparison object with which the unordered_multimap was constructed.

Definition at line 1787 of file unordered_map.h.

## load_factor()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

float std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::load_factor | ( |  | ) | const

inline noexcept

Returns the average number of elements per bucket.

Definition at line 1924 of file unordered_map.h.

## max_bucket_count()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

size_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::max_bucket_count | ( |  | ) | const

inline noexcept

Returns the maximum number of buckets of the unordered_multimap.

Definition at line 1847 of file unordered_map.h.

## max_load_factor() [1/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

float std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::max_load_factor | ( |  | ) | const

inline noexcept

Returns a positive number that the unordered_multimap tries to keep the load factor less than or equal to.

Definition at line 1930 of file unordered_map.h.

## max_load_factor() [2/2]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

void std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::max_load_factor | ( | float | __z | ) |

inline

Change the unordered_multimap maximum load factor.

Parameters

  __z | The new maximum load factor.

Definition at line 1938 of file unordered_map.h.

## max_size()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

size_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::max_size | ( |  | ) | const

inline noexcept

Returns the maximum size of the unordered_multimap.

Definition at line 1447 of file unordered_map.h.

## operator=() [1/3]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

unordered_multimap& std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::operator= | ( | const unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc > & |  | ) |

default

Copy assignment operator.

## operator=() [2/3]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

unordered_multimap& std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::operator= | ( | unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc > && |  | ) |

default

Move assignment operator.

## operator=() [3/3]

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

unordered_multimap& std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::operator= | ( | initializer_list< value_type > | __l | ) |

inline

Unordered_multimap list assignment operator.

Parameters

  __l | An initializer_list.

This function fills an unordered_multimap with copies of the elements in the initializer list __l.

Note that the assignment completely changes the unordered_multimap and that the resulting unordered_multimap's size is the same as the number of elements assigned.

Definition at line 1422 of file unordered_map.h.

## rehash()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

void std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::rehash | ( | size_type | __n | ) |

inline

May rehash the unordered_multimap.

Parameters

  __n | The new number of buckets.

Rehash will occur only if the new number of buckets respect the unordered_multimap maximum load factor.

Definition at line 1949 of file unordered_map.h.

## reserve()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

void std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::reserve | ( | size_type | __n | ) |

inline

Prepare the unordered_multimap for a specified number of elements.

Parameters

  __n | Number of elements required.

Same as rehash(ceil(n / max_load_factor())).

Definition at line 1960 of file unordered_map.h.

## size()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

size_type std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::size | ( |  | ) | const

inline noexcept

Returns the size of the unordered_multimap.

Definition at line 1442 of file unordered_map.h.

## swap()

template<typename _Key, typename _Tp, typename _Hash = hash<_Key>, typename _Pred = equal_to<_Key>, typename _Alloc = allocator<std::pair<const _Key, _Tp>>>

void std::unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc >::swap | ( | unordered_multimap< _Key, _Tp, _Hash, _Pred, _Alloc > & | __x | ) |

inline noexcept

Swaps data with another unordered_multimap.

Parameters

  __x | An unordered_multimap of the same element and allocator types.

This exchanges the elements between two unordered_multimap in constant time. Note that the global std::swap() function is specialized such that std::swap(m1,m2) will feed to this function.

Definition at line 1739 of file unordered_map.h.

The documentation for this class was generated from the following file:

- unordered_map.h