:relfileprefix: ../../../
[#boost-urls-param_view-2constructor]

== xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/param_view.adoc[pass:[param_view]]::param_view

  


Constructor



=== Synopsis
  

[source,cpp,subs="verbatim,macros,-callouts"]
----
constexpr
xref:boost/urls/param_view/2constructor-07a.adoc[pass:[param_view]]() = default;
----

[source,cpp,subs="verbatim,macros,-callouts"]
----
template<class OptionalString>
xref:boost/urls/param_view/2constructor-01.adoc[pass:[param_view]](
    core::string_view key,
    OptionalString const& value) noexcept;
----

[source,cpp,subs="verbatim,macros,-callouts"]
----
xref:boost/urls/param_view/2constructor-07e.adoc[pass:[param_view]](xref:boost/urls/param.adoc[param] const& other) noexcept;
----

[source,cpp,subs="verbatim,macros,-callouts"]
----
xref:boost/urls/param_view/2constructor-03.adoc[pass:[param_view]](
    core::string_view key_,
    core::string_view value_,
    bool has_value_) noexcept;
----
  
=== Description


Default constructed query parameters
have an empty key and no value.
[,cpp]
----
param_view qp;
----
[,cpp]
----
this->key == "" && this->value == "" && this->has_value == false
----

=== Constant.

=== Throws nothing.




=== Parameters

|===
| Name | Description 

| *key,*
| 
value The key and value to set.

| *other*
| 
The param to reference

|===