params

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.

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>