[#bsl-map-0a7-try_emplace-08]
= xref:bsl.adoc[bsl]::xref:bsl/map-0a7.adoc[map]::try_emplace
:relfileprefix: ../../
:mrdocs:

Try to emplace an element with transparent `key`.

== Synopsis

Declared in `<bslstl_map.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<
    class LOOKUP_KEY,
    class... Args>
xref:bsl/pair-0b.adoc[pair<iterator, bool>]
try_emplace(
    LOOKUP_KEY&& key,
    Args&&... args)
requires BloombergLP::bslmf::IsTransparentPredicate<COMPARATOR,
                                                   LOOKUP_KEY>::value &&
        !bsl::is_convertible<LOOKUP_KEY&&, const_iterator>::value &&
        !bsl::is_convertible<LOOKUP_KEY&&, iterator>::value;
----

== Description

If a key equivalent to the specified `key` already exists in this map, return a pair containing an iterator referring to the existing item and `false`. Otherwise, insert into this map a newly‐created entry constructed from `key` and the specified `args`, and return a pair containing an iterator referring to the newly‐created entry and `true`. This overload participates in overload resolution only when `LOOKUP_KEY` is a transparent lookup key for `COMPARATOR`.

== Return Value

pair of iterator and whether a new element was inserted

== Parameters

[cols="1,4"]
|===
| Name| Description
| *key*
| transparent key for the element to emplace
| *args*
| constructor arguments for the mapped value
|===


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