Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for a snapshot of the master branch, built from commit 9fc5439165.
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params_ref

A view representing query parameters in a URL.

Synopsis

Defined in header <boost/url/params_ref.hpp>

class params_ref :
    public params_base
Types

Name

Description

const_iterator

A Bidirectional iterator to a query parameter.

const_reference

The reference type.

difference_type

A signed integer type used to represent differences.

iterator

A Bidirectional iterator to a query parameter.

reference

The reference type.

size_type

An unsigned integer type to represent sizes.

value_type

The value type.

Member Functions

Name

Description

append

Append elements.

assign

Assign elements.

begin

Return an iterator to the beginning.

buffer

Return the referenced character buffer.

clear

Clear the contents of the container.

contains

Return true if a matching key exists.

count

Return the number of matching keys.

empty

Return true if there are no params.

end

Return an iterator to the end.

erase

Erase elements.

find

Find a matching key.

find_last

Find a matching key.

insert

Insert elements.

operator=

Assignment.

operator params_view

Conversion.

params_ref [constructor]

Constructor.

replace

Replace elements.

set

Set a value.

size

Return the number of params.

unset

Remove the value on an element.

url

Return the referenced url.

Static Member Functions

Name

Description

max_size

Return the maximum number of characters possible.

Description

Objects of this type are used to interpret the query parameters as a bidirectional view of key/value pairs. The view does not retain ownership of the elements and instead references the original url. The caller is responsible for ensuring that the lifetime of the referenced url extends until it is no longer referenced. The view is modifiable; calling non-const members will cause changes to the referenced url.

The strings produced when iterators are dereferenced belong to the iterator and become invalidated when that particular iterator is incremented, decremented, or destroyed. Any percent-escapes in returned strings are decoded first. Strings passed to member functions do not contain percent-escapes; the percent character ('') is treated as a literal percent.

Example
url u( "?first=John&last=Doe" );

params_ref p = u.params();
Iterator Invalidation

Changes to the underlying character buffer can invalidate iterators which reference it. Modifications made through the container will invalidate some iterators to the underlying character buffer: * append : Only end(). * assign, clear, operator= : All elements. * erase : Erased elements and all elements after (including end()). * insert : All elements at or after the insertion point (including end()). * replace, set : Modified elements and all elements after (including end()).

Convenience header <boost/url.hpp>


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