[#bsl-unordered_map-02b-try_emplace-05e]
= xref:bsl.adoc[bsl]::xref:bsl/unordered_map-02b.adoc[unordered_map]::try_emplace
:relfileprefix: ../../
:mrdocs:

Emplace a value for `key` at `hint` if missing.

== Synopsis

Declared in `<bslstl_unorderedmap.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class... Args>
xref:bsl/unordered_map-02b/iterator.adoc[iterator]
try_emplace(
    xref:bsl/unordered_map-02b/const_iterator.adoc[const_iterator] hint,
    KEY const& key,
    Args&&... args);
----

== Description

Emplace a value for `key` if no equivalent key already exists.

If a key equivalent to the specified `key` already exists in this unordered_map, return an iterator referring to the existing item. Otherwise, insert into this map a newly‐created `value_type` object, constructed from `key` and the specified `args`, and return an iterator referring to the newly‐created entry. Use the specified `hint` as a starting point for checking to see if the key already in the unordered_map. This method requires that the (template parameter) types `KEY` and `VALUE` are `emplace‐constructible` from `key` and `args` respectively. For C++03, `VALUE` must also be `copy‐constructible`.

== Return Value

iterator to the existing or newly inserted element

== Parameters

[cols="1,4"]
|===
| Name| Description
| *hint*
| iterator hint for insertion
| *key*
| key to look up
| *args*
| constructor arguments for the new element
|===


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