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


Constructor

== Synopsis


Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/params_view.hpp#L80[boost/url/params_view.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/params_view/2constructor-0d.adoc[params_view]() = default;
----

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[source,cpp,subs="verbatim,replacements,macros,-callouts"]
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constexpr
xref:boost/urls/params_view/2constructor-091.adoc[params_view](xref:boost/urls/params_view.adoc[params_view] const& other) = default;
----

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[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/params_view/2constructor-01.adoc[params_view](
    xref:boost/urls/params_view.adoc[params_view] const& other,
    xref:boost/urls/encoding_opts.adoc[encoding_opts] opt) noexcept;
----

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[source,cpp,subs="verbatim,replacements,macros,-callouts"]
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xref:boost/urls/params_view/2constructor-09a.adoc[params_view](core::string_view s);
----

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[source,cpp,subs="verbatim,replacements,macros,-callouts"]
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xref:boost/urls/params_view/2constructor-04.adoc[params_view](
    core::string_view s,
    xref:boost/urls/encoding_opts.adoc[encoding_opts] opt);
----

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== Description


Default‐constructed params have        zero elements.


=== Example

[,cpp]
----
params_view qp;
----

=== Effects

[,cpp]
----
return params_view( "" );
----

=== Complexity

Constant.


=== Exception Safety

Throws nothing.



== Exceptions


|===
| Name | Thrown on

| `system_error`
| `s` contains an invalid query parameter        string.


|===

== Parameters


|===
| Name | Description

| *s*
| The string to parse.


| *opt*
| The options for decoding. If        this parameter is omitted, `space_as_plus`        is used.


|===



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