[#bsl-unordered_map-02b-at-0f]
= xref:bsl.adoc[bsl]::xref:bsl/unordered_map-02b.adoc[unordered&lowbar;map]::at
:relfileprefix: ../../
:mrdocs:

`at` overloads

== Synopses

Declared in `&lt;bslstl&lowbar;unorderedmap&period;h&gt;`

Return a modifiable reference to the mapped value for `key`&period;


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
add&lowbar;lvalue&lowbar;reference&lt;VALUE&gt;::type
xref:bsl/unordered_map-02b/at-06.adoc[at](xref:bsl/unordered_map-02b/key_type.adoc[key&lowbar;type] const& key);
----

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

Return a const reference to the mapped value for `key`&period;


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
add&lowbar;lvalue&lowbar;reference&lt;VALUE const&gt;::type
xref:bsl/unordered_map-02b/at-0b.adoc[at](xref:bsl/unordered_map-02b/key_type.adoc[key&lowbar;type] const& key) const;
----

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

Return a modifiable reference to the mapped value for `key`&period;


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template&lt;class LOOKUP&lowbar;KEY&gt;
add&lowbar;lvalue&lowbar;reference&lt;VALUE&gt;::type
xref:bsl/unordered_map-02b/at-07.adoc[at](LOOKUP&lowbar;KEY const& key)
requires BloombergLP&colon;&colon;bslmf&colon;&colon;IsTransparentPredicate&lt;HASH, LOOKUP&lowbar;KEY&gt;&colon;&colon;value
        &amp;&amp; BloombergLP&colon;&colon;bslmf&colon;&colon;IsTransparentPredicate&lt;EQUAL,LOOKUP&lowbar;KEY&gt;&colon;&colon;value;
----

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

Return a const reference to the mapped value for an equivalent `key`&period;


[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template&lt;class LOOKUP&lowbar;KEY&gt;
add&lowbar;lvalue&lowbar;reference&lt;VALUE const&gt;::type
xref:bsl/unordered_map-02b/at-02.adoc[at](LOOKUP&lowbar;KEY const& key) const
requires BloombergLP&colon;&colon;bslmf&colon;&colon;IsTransparentPredicate&lt;HASH, LOOKUP&lowbar;KEY&gt;&colon;&colon;value
        &amp;&amp; BloombergLP&colon;&colon;bslmf&colon;&colon;IsTransparentPredicate&lt;EQUAL,LOOKUP&lowbar;KEY&gt;&colon;&colon;value;
----

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

== 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]#
