[#bsl-unordered_map-02b-2constructor-0f0]
= xref:bsl.adoc[bsl]::xref:bsl/unordered_map-02b.adoc[unordered_map]::unordered_map
:relfileprefix: ../../
:mrdocs:

Constructors

== Synopses

Declared in `<bslstl_unorderedmap.h>`

Create an empty unordered map.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/unordered_map-02b/2constructor-0c.adoc[unordered_map]();
----

[.small]#xref:bsl/unordered_map-02b/2constructor-0c.adoc[_» more..._]#

Create an unordered map as a copy of `original`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/unordered_map-02b/2constructor-03.adoc[unordered_map](xref:bsl/unordered_map-02b.adoc[unordered_map] const& original);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-03.adoc[_» more..._]#

Create an unordered map by moving from `original`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/unordered_map-02b/2constructor-05.adoc[unordered_map](xref:BloombergLP/bslmf/MovableRef.adoc[BloombergLP::bslmf::MovableRef<unordered_map>] original);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-05.adoc[_» more..._]#

Create an empty unordered map using `basicAllocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
explicit
xref:bsl/unordered_map-02b/2constructor-04.adoc[unordered_map](ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-04.adoc[_» more..._]#

Create an empty unordered map with bucket count and allocator.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/unordered_map-02b/2constructor-06.adoc[unordered_map](
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-06.adoc[_» more..._]#

Create an unordered map by moving from `original` using `basicAllocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/unordered_map-02b/2constructor-0ee.adoc[unordered_map](
    xref:BloombergLP/bslmf/MovableRef.adoc[BloombergLP::bslmf::MovableRef<unordered_map>] original,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-0ee.adoc[_» more..._]#

Create a copy of `original` using `basicAllocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/unordered_map-02b/2constructor-093.adoc[unordered_map](
    xref:bsl/unordered_map-02b.adoc[unordered_map] const& original,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-093.adoc[_» more..._]#

Create an unordered map from `values` using `basicAllocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<>
requires bsl::IsStdAllocator_v<ALLOCATOR>
xref:bsl/unordered_map-02b/2constructor-0a.adoc[unordered_map](
    std::initializer_list<value_type> values,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-0a.adoc[_» more..._]#

Create an empty unordered map with hash and allocator.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:bsl/unordered_map-02b/2constructor-0fd.adoc[unordered_map](
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    HASH const& hashFunction,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-0fd.adoc[_» more..._]#

Create an unordered map from `values` with bucket count and allocator.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<>
requires bsl::IsStdAllocator_v<ALLOCATOR>
xref:bsl/unordered_map-02b/2constructor-0b.adoc[unordered_map](
    std::initializer_list<value_type> values,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-0b.adoc[_» more..._]#

Create an unordered map from `[first, last)]` using `basicAllocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class INPUT_ITERATOR>
xref:bsl/unordered_map-02b/2constructor-095.adoc[unordered_map](
    INPUT_ITERATOR first,
    INPUT_ITERATOR last,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-095.adoc[_» more..._]#

Create an unordered map from `range` using `basicAllocator`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class RANGE>
xref:bsl/unordered_map-02b/2constructor-0fb.adoc[unordered_map](
    std::from_range_t tag,
    RANGE&& range,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-0fb.adoc[_» more..._]#

Create an empty unordered map.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
explicit
xref:bsl/unordered_map-02b/2constructor-07b.adoc[unordered_map](
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    HASH const& hashFunction = HASH(),
    EQUAL const& keyEqual = EQUAL(),
    ALLOCATOR const& basicAllocator = ALLOCATOR());
----

[.small]#xref:bsl/unordered_map-02b/2constructor-07b.adoc[_» more..._]#

Create an unordered map from `values` with hash and allocator.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<>
requires std::is_invocable_v<HASH, const KEY &> && bsl::IsStdAllocator_v<ALLOCATOR>
xref:bsl/unordered_map-02b/2constructor-028.adoc[unordered_map](
    std::initializer_list<value_type> values,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    HASH const& hashFunction,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-028.adoc[_» more..._]#

Create an unordered map from `[first, last)]` with bucket count.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class INPUT_ITERATOR>
xref:bsl/unordered_map-02b/2constructor-00.adoc[unordered_map](
    INPUT_ITERATOR first,
    INPUT_ITERATOR last,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-00.adoc[_» more..._]#

Create an unordered map from `range` with bucket count and allocator.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class RANGE>
xref:bsl/unordered_map-02b/2constructor-085.adoc[unordered_map](
    std::from_range_t tag,
    RANGE&& range,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-085.adoc[_» more..._]#

Create an unordered map from the specified `values` initializer list.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<>
requires std::is_invocable_v<HASH, const KEY &> && std::is_invocable_v<EQUAL, const KEY &, const KEY &> && bsl::IsStdAllocator_v<ALLOCATOR>
xref:bsl/unordered_map-02b/2constructor-02a.adoc[unordered_map](
    std::initializer_list<value_type> values,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets = 0,
    HASH const& hashFunction = HASH(),
    EQUAL const& keyEqual = EQUAL(),
    ALLOCATOR const& basicAllocator = ALLOCATOR());
----

[.small]#xref:bsl/unordered_map-02b/2constructor-02a.adoc[_» more..._]#

Create an unordered map from `[first, last)]` with hash and allocator.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class INPUT_ITERATOR>
xref:bsl/unordered_map-02b/2constructor-0ef.adoc[unordered_map](
    INPUT_ITERATOR first,
    INPUT_ITERATOR last,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    HASH const& hashFunction,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-0ef.adoc[_» more..._]#

Create an unordered map from `range` with hash and allocator.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class RANGE>
xref:bsl/unordered_map-02b/2constructor-08d.adoc[unordered_map](
    std::from_range_t tag,
    RANGE&& range,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets,
    HASH const& hashFunction,
    ALLOCATOR const& basicAllocator);
----

[.small]#xref:bsl/unordered_map-02b/2constructor-08d.adoc[_» more..._]#

Create an unordered map from the iterator range `[first, last)]`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class INPUT_ITERATOR>
xref:bsl/unordered_map-02b/2constructor-09b.adoc[unordered_map](
    INPUT_ITERATOR first,
    INPUT_ITERATOR last,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets = 0,
    HASH const& hashFunction = HASH(),
    EQUAL const& keyEqual = EQUAL(),
    ALLOCATOR const& basicAllocator = ALLOCATOR());
----

[.small]#xref:bsl/unordered_map-02b/2constructor-09b.adoc[_» more..._]#

Create an unordered map from the specified `range`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class RANGE>
xref:bsl/unordered_map-02b/2constructor-076.adoc[unordered_map](
    std::from_range_t tag,
    RANGE&& range,
    xref:bsl/unordered_map-02b/size_type.adoc[size_type] initialNumBuckets = 0,
    HASH const& hashFunction = HASH(),
    EQUAL const& keyEqual = EQUAL(),
    ALLOCATOR const& basicAllocator = ALLOCATOR());
----

[.small]#xref:bsl/unordered_map-02b/2constructor-076.adoc[_» more..._]#

== Parameters

[cols="1,4"]
|===
| Name| Description
| *original*
| unordered map to copy or move from
| *basicAllocator*
| allocator used to supply memory
| *initialNumBuckets*
| initial number of buckets
| *values*
| initializer list of values to insert
| *hashFunction*
| hash functor
| *first*
| start of the range
| *last*
| end of the range (one past last)
| *tag*
| disambiguation tag for from‐range construction
| *range*
| input range of values to insert
| *keyEqual*
| key‐equality functor
|===


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