:relfileprefix: ../../../
[#9AD6406FF4EAA95725C1EA110E914F0306FEA4F0]

= Function params_view::params_view

pass:v,q[Constructor]


== Synopsis

Declared in header `</boost/url/params_view.hpp#L186[boost/url/params_view.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
params_view(string_view s);
----

== Description

pass:v,q[This function constructs params from] pass:v,q[a valid query parameter string, which]
pass:v,q[can contain percent escapes. Unlike]
pass:v,q[the parameters in URLs, the string]
pass:v,q[passed here should not start with "?".]
pass:v,q[Upon construction, the view references]
pass:v,q[the character buffer pointed to by `s`.]
pass:v,q[The caller is responsible for ensuring]
pass:v,q[that the lifetime of the buffer extends]
pass:v,q[until it is no longer referenced.]

=== Example
[,cpp]
----
params_view qp( "first=John&last=Doe" );
----

=== Effects
[,cpp]
----
return parse_query( s ).value();
----

=== Postconditions
[,cpp]
----
this->buffer().data() == s.data()
----

=== Complexity
pass:v,q[Linear in `s`.]

=== Exception Safety
pass:v,q[Exceptions thrown on invalid input.]

=== BNF
[,cpp]
----
query-params    = [ query-param ] *( "&" query-param )

query-param     = key [ "=" value ]
----

=== Specification

* link:https://datatracker.ietf.org/doc/html/rfc3986#section-3.4[3.4.  Query]



== Return Value

* `void` 


== Parameters

|===
| Name | Type 

| *s*
| `string_view`

|===