[#BloombergLP-bslstl-HashTable-09-insertIfMissing-079]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslstl.adoc[bslstl]::xref:BloombergLP/bslstl/HashTable-09.adoc[HashTable<UnorderedMapKeyConfiguration<basic_string<char> const, pair<basic_string<char> const, Json>>, TransparentHash, TransparentEqualTo, allocator<pair<basic_string<char> const, Json>>>]::insertIfMissing
:relfileprefix: ../../../
:mrdocs:

Insert into this hash‐table a newly‐created `ValueType` object, constructed by forwarding the specified `key` and a default‐constructed object of the type `ValueType::second_type`, to the corresponding constructor of `ValueType`, if `key` does not already exist in this hash‐table. Return the address of the (possibly newly created and inserted) element in this hash‐table whose key is equivalent to `key`. If this hash‐table contains more than one element with the supplied `key`, return the first such element (from the contiguous sequence of elements having a matching key). Additional buckets are allocated, as needed, to preserve the invariant `loadFactor <= maxLoadFactor`. If this function tries to allocate a number of buckets larger than can be represented by this hash table's `SizeType`, a `std::length_error` exception is thrown. This method requires that the `ValueType` defined in the (template parameter) type `KEY_CONFIG` be `emplace‐constructible` into this hash‐table from a `pair` of arguments representing the key and value, respectively (see {Requirements on `KEY_CONFIG`});

== Synopsis

Declared in `<bslstl_hashtable.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:BloombergLP/bslalg/BidirectionalLink.adoc[bslalg::BidirectionalLink]*
insertIfMissing(xref:BloombergLP/bslstl/HashTable-09/KeyType.adoc[KeyType] const& key);
----


[.small]#Created with https://www.mrdocs.com[MrDocs]#