[#boost-urls-url-set_params]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/url.adoc[url]::set_params
:relfileprefix: ../../../
:mrdocs:


Set the query params

== Synopsis


Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/url.hpp#L475[boost/url/url.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:boost/urls/url.adoc[url]&
set_params(
    std::initializer_list<xref:boost/urls/param_view.adoc[param_view]> ps,
    xref:boost/urls/encoding_opts.adoc[encoding_opts] opts = {});
----

== Description


This sets the query params to the list        of param_view, which can be empty.

An empty list of params is distinct from        having no params.

Reserved characters in the string are        percent‐escaped in the result.


=== Example

[,cpp]
----
assert( url( "http://example.com" ).set_params( {"id", "42"} ).query() == "id=42" );
----

=== Postconditions

[,cpp]
----
this->has_query() == true
----

=== Exception Safety

Strong guarantee.        Calls to allocate may throw.


=== Complexity

Linear.


=== BNF

[,cpp]
----
query           = *( pchar / "/" / "?" )

query-param     = key [ "=" value ]
query-params    = [ query-param ] *( "&" query-param )
----

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.4
            >3.4.  Query (rfc3986)</a>
        @li <a href=[&colon;&sol;&sol;en&period;wikipedia&period;org&sol;wiki&sol;Query&lowbar;string&quot;            &gt;Query string (Wikipedia)]



== Parameters


|===
| Name | Description

| *ps*
| The params to set&period;


| *opts*
| The options for encoding&period;


|===

== See Also


xref:boost/urls/url_base/encoded_params-06.adoc[encoded&lowbar;params],            xref:boost/urls/url_base/remove_query.adoc[remove&lowbar;query],            xref:boost/urls/url_base/set_encoded_query.adoc[set&lowbar;encoded&lowbar;query],            xref:boost/urls/url_base/set_query.adoc[set&lowbar;query]&period;






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