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