[#bsl-unordered_map-02b-2constructor-076]
= xref:bsl.adoc[bsl]::xref:bsl/unordered_map-02b.adoc[unordered_map]::unordered_map
:relfileprefix: ../../
:mrdocs:

Create an unordered set, and insert each `value_type` object in the specified `range`, ignoring those keys having a key equivalent to that which appears earlier in the `range`. Optionally specify an `initialNumBuckets` indicating the initial size of the array of buckets of this container. If `initialNumBuckets` is not supplied, an implementation‐defined value is used. Optionally specify a `hashFunction` used to generate the hash values for each key value contained in this set. If `hashFunction` is not supplied, a default‐constructed object of the (template parameter) type `HASH` is used. Optionally specify a key‐equality functor `keyEqual` used to determine whether two keys have the same value. If `keyEqual` is not supplied, a default‐constructed object of the (template parameter) type `EQUAL` is used. Optionally specify a `basicAllocator` used to supply memory. If `basicAllocator` is not supplied, a default‐constructed object of the (template parameter) type `ALLOCATOR` is used. If the type `ALLOCATOR` is `bsl::allocator` (the default), then `basicAllocator`, if supplied, shall be convertible to `bslma::Allocator *`. If the type `ALLOCATOR` is `bsl::allocator` and `basicAllocator` is not supplied, the currently installed default allocator is used. This operation has `O[N]` complexity, where `N` is the number of elements in `range`. Note that `RANGE` must meet the requirements of an input range and the values from `range` must have a type matching or convertible to `value_type`.

== Synopsis

Declared in `<bslstl_unorderedmap.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class RANGE>
unordered_map(
    std::from_range_t,
    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());
----


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