[#bsl-unordered_map-02b-at-0f]
= xref:bsl.adoc[bsl]::xref:bsl/unordered_map-02b.adoc[unordered_map]::at
:relfileprefix: ../../
:mrdocs:

`at` overloads

== Synopses

Declared in `<bslstl_unorderedmap.h>`

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


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
add_lvalue_reference<VALUE>::type
xref:bsl/unordered_map-02b/at-06.adoc[at](xref:bsl/unordered_map-02b/key_type.adoc[key_type] const& key);
----

[.small]#xref:bsl/unordered_map-02b/at-06.adoc[_» more..._]#

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


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
add_lvalue_reference<VALUE const>::type
xref:bsl/unordered_map-02b/at-0b.adoc[at](xref:bsl/unordered_map-02b/key_type.adoc[key_type] const& key) const;
----

[.small]#xref:bsl/unordered_map-02b/at-0b.adoc[_» more..._]#

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


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class LOOKUP_KEY>
add_lvalue_reference<VALUE>::type
xref:bsl/unordered_map-02b/at-07.adoc[at](LOOKUP_KEY const& key)
requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value;
----

[.small]#xref:bsl/unordered_map-02b/at-07.adoc[_» more..._]#

Return a const reference to the mapped value for an equivalent `key`.


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class LOOKUP_KEY>
add_lvalue_reference<VALUE const>::type
xref:bsl/unordered_map-02b/at-02.adoc[at](LOOKUP_KEY const& key) const
requires BloombergLP::bslmf::IsTransparentPredicate<HASH, LOOKUP_KEY>::value
        && BloombergLP::bslmf::IsTransparentPredicate<EQUAL,LOOKUP_KEY>::value;
----

[.small]#xref:bsl/unordered_map-02b/at-02.adoc[_» more..._]#

== Return Value

* modifiable reference to the mapped value
* const reference to the mapped value

== Parameters

[cols="1,4"]
|===
| Name| Description
| *key*
| key to look up
|===


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