[#bsl-unordered_multiset-06c]
= xref:bsl.adoc[bsl]::unordered_multiset
:relfileprefix: ../
:mrdocs:

This class template implements a value‐semantic container type holding an unordered multiset of values (of template parameter type `KEY`).

== Synopsis

Declared in `<bslstl_unorderedmultiset.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class KEY,
    class HASH = xref:bsl/hash-06.adoc[bsl::hash<KEY>],
    class EQUAL = xref:bsl/equal_to-0d.adoc[bsl::equal_to<KEY>],
    class ALLOCATOR = xref:bsl/allocator-0df.adoc[bsl::allocator<KEY>]>
class unordered_multiset;
----

== Description

This class: * supports a complete set of _value‐semantic_ operations

* except for BDEX serialization * is _exception‐neutral_ (agnostic except for the `at` method) * is _alias‐safe_ * is `const` _thread‐safe_ For terminology see {`bsldoc_glossary`}.

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/unordered_multiset-06c/allocator_type.adoc[`allocator_type`] 
| This `typedef` is an alias to the (template parameter) `ALLOCATOR`.
| xref:bsl/unordered_multiset-06c/const_iterator.adoc[`const_iterator`] 
| This `typedef` is an alias to `iterator`.
| xref:bsl/unordered_multiset-06c/const_local_iterator.adoc[`const_local_iterator`] 
| This `typedef` is an alias to `local_iterator`.
| xref:bsl/unordered_multiset-06c/const_pointer.adoc[`const_pointer`] 
| This `typedef` is an alias to the allocator const‐pointer type.
| xref:bsl/unordered_multiset-06c/const_reference.adoc[`const_reference`] 
| This `typedef` is an alias for `const_reference`.
| xref:bsl/unordered_multiset-06c/difference_type.adoc[`difference_type`] 
| This `typedef` is an alias to the allocator difference type.
| xref:bsl/unordered_multiset-06c/hasher.adoc[`hasher`] 
| This `typedef` is an alias to the (template parameter) `HASH` type.
| xref:bsl/unordered_multiset-06c/iterator.adoc[`iterator`] 
| This `typedef` is an alias to the hash‐table iterator type.
| xref:bsl/unordered_multiset-06c/key_equal.adoc[`key_equal`] 
| This `typedef` is an alias to the (template parameter) `EQUAL` type.
| xref:bsl/unordered_multiset-06c/key_type.adoc[`key_type`] 
| This `typedef` is an alias to the (template parameter) `KEY` type.
| xref:bsl/unordered_multiset-06c/local_iterator.adoc[`local_iterator`] 
| This `typedef` is an alias to the hash‐table local iterator type.
| xref:bsl/unordered_multiset-06c/pointer.adoc[`pointer`] 
| This `typedef` is an alias to the allocator pointer type.
| xref:bsl/unordered_multiset-06c/reference.adoc[`reference`] 
| This `typedef` is an alias to `value_type&`.
| xref:bsl/unordered_multiset-06c/size_type.adoc[`size_type`] 
| This `typedef` is an alias to the allocator size type.
| xref:bsl/unordered_multiset-06c/value_type.adoc[`value_type`] 
| This `typedef` is an alias to `key_type`.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/unordered_multiset-06c/2constructor-0ab.adoc[`unordered_multiset`]         [.small]#[constructor]#
| Constructors
| xref:bsl/unordered_multiset-06c/2destructor.adoc[`~unordered_multiset`] [.small]#[destructor]#
| Destroy this object.
| xref:bsl/unordered_multiset-06c/operator_assign-0c4.adoc[`operator=`] 
| Assignment operators
| xref:bsl/unordered_multiset-06c/begin-0f2.adoc[`begin`] 
| `begin` overloads
| xref:bsl/unordered_multiset-06c/bucket-0a.adoc[`bucket`] 
| Return the bucket index for the specified `key`.
| xref:bsl/unordered_multiset-06c/bucket_count.adoc[`bucket_count`] 
| Return the number of buckets in the array of buckets maintained by this unordered multiset.
| xref:bsl/unordered_multiset-06c/bucket_size.adoc[`bucket_size`] 
| Return the number of elements in the bucket at `index`.
| xref:bsl/unordered_multiset-06c/cbegin-02.adoc[`cbegin`] 
| `cbegin` overloads
| xref:bsl/unordered_multiset-06c/cend-0f.adoc[`cend`] 
| `cend` overloads
| xref:bsl/unordered_multiset-06c/clear.adoc[`clear`] 
| Remove all entries from this unordered multiset. Note that the container is empty after this call, but allocated memory may be retained for future use.
| xref:bsl/unordered_multiset-06c/contains-01.adoc[`contains`] 
| Return whether this unordered multiset contains `key`.
| xref:bsl/unordered_multiset-06c/count-00d.adoc[`count`] 
| Return the number of elements equivalent to `key`.
| xref:bsl/unordered_multiset-06c/emplace.adoc[`emplace`] 
| Emplace a newly constructed element into this unordered multiset.
| xref:bsl/unordered_multiset-06c/emplace_hint.adoc[`emplace_hint`] 
| Emplace a newly constructed element near `hint`.
| xref:bsl/unordered_multiset-06c/empty.adoc[`empty`] 
| Return `true` if this unordered multiset contains no elements, and `false` otherwise.
| xref:bsl/unordered_multiset-06c/end-06.adoc[`end`] 
| `end` overloads
| xref:bsl/unordered_multiset-06c/equal_range-00.adoc[`equal_range`] 
| `equal_range` overloads
| xref:bsl/unordered_multiset-06c/erase-03.adoc[`erase`] 
| `erase` overloads
| xref:bsl/unordered_multiset-06c/find-0c.adoc[`find`] 
| `find` overloads
| xref:bsl/unordered_multiset-06c/get_allocator.adoc[`get_allocator`] 
| Return (a copy of) the allocator used for memory allocation by this unordered multiset.
| xref:bsl/unordered_multiset-06c/hash_function.adoc[`hash_function`] 
| Return (a copy of) the hash unary functor used by this unordered multiset to generate a hash value (of type `size_t`) for a `key_type` object.
| xref:bsl/unordered_multiset-06c/insert-09.adoc[`insert`] 
| `insert` overloads
| xref:bsl/unordered_multiset-06c/insert_range.adoc[`insert_range`] 
| Insert each element from the specified `range`.
| xref:bsl/unordered_multiset-06c/key_eq.adoc[`key_eq`] 
| Return (a copy of) the key‐equality binary functor that returns `true` if the value of two `key_type` objects are equivalent, and `false` otherwise.
| xref:bsl/unordered_multiset-06c/load_factor.adoc[`load_factor`] 
| Return the current load factor of this container.
| xref:bsl/unordered_multiset-06c/max_bucket_count.adoc[`max_bucket_count`] 
| Return a theoretical upper bound on the number of buckets.
| xref:bsl/unordered_multiset-06c/max_load_factor-04.adoc[`max_load_factor`] 
| `max_load_factor` overloads
| xref:bsl/unordered_multiset-06c/max_size.adoc[`max_size`] 
| Return a theoretical upper bound on the size of this container.
| xref:bsl/unordered_multiset-06c/rehash.adoc[`rehash`] 
| Rehash this container to at least `numBuckets` buckets.
| xref:bsl/unordered_multiset-06c/reserve.adoc[`reserve`] 
| Reserve capacity for at least `numElements` without rehashing.
| xref:bsl/unordered_multiset-06c/size.adoc[`size`] 
| Return the number of elements in this unordered multiset.
| xref:bsl/unordered_multiset-06c/swap.adoc[`swap`] 
| Exchange the contents of this object with those of `other`.
| xref:bsl/unordered_multiset-06c/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<unordered_multiset, IsBitwiseMoveable, ::BloombergLP::bslmf::IsBitwiseMoveable<HashTable>::value>`] 
| Nested trait declaration for `bslmf::IsBitwiseMoveable`.
|===


== Deduction Guides

[cols="1,4"]
|===
| Name| Description
| xref:bsl/unordered_multiset-05.adoc[`unordered_multiset<KEY>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-09e.adoc[`unordered_multiset<KEY>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-07f.adoc[`unordered_multiset<KEY>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
| xref:bsl/unordered_multiset-07a.adoc[`unordered_multiset<KEY>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
| xref:bsl/unordered_multiset-063.adoc[`unordered_multiset<KEY, HASH>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-0d3.adoc[`unordered_multiset<KEY, HASH>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
| xref:bsl/unordered_multiset-0a9.adoc[`unordered_multiset<KEY, HASH, EQUAL>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-091.adoc[`unordered_multiset<KEY, HASH, EQUAL>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
| xref:bsl/unordered_multiset-009.adoc[`unordered_multiset<KEY, HASH, EQUAL, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-0ab.adoc[`unordered_multiset<KEY, HASH, EQUAL, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
| xref:bsl/unordered_multiset-00df.adoc[`unordered_multiset<KEY, HASH, bsl::equal_to<KEY>, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-0db.adoc[`unordered_multiset<KEY, HASH, bsl::equal_to<KEY>, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
| xref:bsl/unordered_multiset-0d0.adoc[`unordered_multiset<KEY, bsl::hash<KEY>, bsl::equal_to<KEY>, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-00d8.adoc[`unordered_multiset<KEY, bsl::hash<KEY>, bsl::equal_to<KEY>, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from initializer_list `value_type`.
| xref:bsl/unordered_multiset-0e.adoc[`unordered_multiset<KEY, bsl::hash<KEY>, bsl::equal_to<KEY>, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
| xref:bsl/unordered_multiset-02.adoc[`unordered_multiset<KEY, bsl::hash<KEY>, bsl::equal_to<KEY>, ALLOCATOR>`] 
| CTAD guide: deduce `KEY` from iterator `value_type`.
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:bsl/operator_eq-0a2.adoc[bsl::operator==]`
| Return `true` if the specified `lhs` and `rhs` objects have the same value, and `false` otherwise.
|===

== Non-Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/erase_if-074.adoc[`erase_if`]
| Erase all elements in `ms` that satisfy `predicate`.
| xref:bsl/operator_eq-094.adoc[`operator==`]
| Return `true` if `lhs` and `rhs` have the same value.
| xref:bsl/swap-03d7.adoc[`swap`]
| Exchange the values of the specified `a` and `b` objects.
|===


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