[#bsl-select1st]
= xref:bsl.adoc[bsl]::select1st
:relfileprefix: ../
:mrdocs:

This `struct` is a functor that returns the `first` member of its `PAIR` argument.

== Synopsis

Declared in `<bslstp_exfunctional.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class PAIR>
struct select1st;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:bsl/select1st/argument_type.adoc[`argument_type`] 
| This `typedef` is an alias to the (template parameter) `PAIR`.
| xref:bsl/select1st/result_type.adoc[`result_type`] 
| This `typedef` is an alias to `PAIR::first_type`.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:bsl/select1st/operator_call.adoc[`operator()`] 
| Return a reference to the `first` member of the specified `x`.
| xref:bsl/select1st/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<select1st, is_trivially_copyable>`] 
| Declare that `select1st` is trivially copyable.
|===



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