[#BloombergLP-bdlc-FlatHashMap-operator_subs-09]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlc.adoc[bdlc]::xref:BloombergLP/bdlc/FlatHashMap.adoc[FlatHashMap]::operator[]
:relfileprefix: ../../../
:mrdocs:

Return a modifiable reference to the mapped value for `key`.

== Synopsis

Declared in `<bdlc_flathashmap.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class LOOKUP_KEY>
VALUE&
operator[](LOOKUP_KEY&& key)
requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
         && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value;
----

== Description

Return a reference providing modifiable access to the mapped value associated with the a key equivalent to the specified `key` in this map. If this map does not already contain an element eqivalent to `key`, insert an element with the KEY constructed from `std::forward<LOOKUP_KEY>(k)` and a default‐constructed `VALUE`, and return a reference to the newly mapped value.

== Return Value

modifiable reference to the mapped value for `key`

== Parameters

[cols="1,4"]
|===
| Name| Description
| *key*
| transparent key whose mapped value is accessed
|===


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