[#boost-urls-param_pct_view-2constructor]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/param_pct_view.adoc[param_pct_view]::param_pct_view
:relfileprefix: ../../../
:mrdocs:


Constructor

== Synopsis


Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/param.hpp#L697[boost/url/param.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr
xref:boost/urls/param_pct_view/2constructor-00.adoc[param_pct_view]() = default;
----

[.small]#xref:boost/urls/param_pct_view/2constructor-00.adoc[_» more..._]#

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/param_pct_view/2constructor-0e.adoc[param_pct_view](
    xref:boost/urls/pct_string_view.adoc[pct_string_view] key,
    xref:boost/urls/pct_string_view.adoc[pct_string_view] value) noexcept;
----

[.small]#xref:boost/urls/param_pct_view/2constructor-0e.adoc[_» more..._]#

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class OptionalString>
xref:boost/urls/param_pct_view/2constructor-05.adoc[param_pct_view](
    xref:boost/urls/pct_string_view.adoc[pct_string_view] key,
    OptionalString const& value);
----

[.small]#xref:boost/urls/param_pct_view/2constructor-05.adoc[_» more..._]#

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
explicit
xref:boost/urls/param_pct_view/2constructor-03.adoc[param_pct_view](xref:boost/urls/param_view.adoc[param_view] const& p);
----

[.small]#xref:boost/urls/param_pct_view/2constructor-03.adoc[_» more..._]#

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/param_pct_view/2constructor-02.adoc[param_pct_view](
    xref:boost/urls/pct_string_view.adoc[pct_string_view] key,
    xref:boost/urls/pct_string_view.adoc[pct_string_view] value,
    bool has_value) noexcept;
----

[.small]#xref:boost/urls/param_pct_view/2constructor-02.adoc[_» more..._]#

== Description


Default constructed query parameters        have an empty key and no value.


=== Example

[,cpp]
----
param_pct_view qp;
----

=== Postconditions

[,cpp]
----
this->key == "" && this->value == "" && this->has_value == false
----

=== Complexity

Constant.


=== Exception Safety

Throws nothing.



== Exceptions


|===
| Name | Thrown on

| `system_error`
| `key` or `value` contains an invalid percent‐encoding.


|===

== Template Parameters


|===
| Name | Description

| *OptionalString*
| An optional        `core::string_view` type, such as        `boost::optional<core::string_view>` or        `std::optional<core::string_view>`.


|===

== Parameters


|===
| Name | Description

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


| *p*
| The param to construct from.


|===



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