# Poco::Net

# class NameValueCollection

Library: Net
Package: Messages
Header: Poco/Net/NameValueCollection.h

## Description

A collection of name-value pairs that are used in various internet protocols like HTTP and SMTP.

The name is case-insensitive.

There can be more than one name-value pair with the same name.

## Inheritance

Known Derived Classes: HTMLForm, HTTPAuthenticationParams, HTTPMessage, HTTPRequest, HTTPResponse, HTTPServerRequest, HTTPServerRequestImpl, HTTPServerResponse, HTTPServerResponseImpl, MailMessage, MessageHeader

## Member Summary

Member Functions: add, begin, clear, empty, end, erase, find, get, has, operator =, operator [], set, size, swap

## Types Aliases

### ConstIterator

using ConstIterator = HeaderMap::ConstIterator;

### HeaderMap

using HeaderMap = Poco::ListMap < std::string, std::string >;

### Iterator

using Iterator = HeaderMap::Iterator;

## Constructors

### NameValueCollection

NameValueCollection();

Creates an empty NameValueCollection.

### NameValueCollection

NameValueCollection(
const NameValueCollection & nvc
);

Creates a NameValueCollection by copying another one.

### NameValueCollection

NameValueCollection(
NameValueCollection && nvc
) noexcept;

Creates a NameValueCollection by moving another one.

## Destructor

### ~NameValueCollection

virtual ~NameValueCollection();

Destroys the NameValueCollection.

## Member Functions

### add

void add(
const std::string & name,
const std::string & value
);

Adds a new name-value pair with the given name and value.

### begin

ConstIterator begin() const;

Returns an iterator pointing to the begin of the name-value pair collection.

### clear

void clear();

Removes all name-value pairs and their values.

### empty

bool empty() const;

Returns true iff the header does not have any content.

### end

ConstIterator end() const;

Returns an iterator pointing to the end of the name-value pair collection.

### erase

void erase(
const std::string & name
);

Removes all name-value pairs with the given name.

### find

ConstIterator find(
const std::string & name
) const;

Returns an iterator pointing to the first name-value pair with the given name.

### get

const std::string & get(
const std::string & name
) const;

Returns the value of the first name-value pair with the given name.

Throws a NotFoundException if the name-value pair does not exist.

### get

const std::string & get(
const std::string & name,
const std::string & defaultValue
) const;

Returns the value of the first name-value pair with the given name. If no value with the given name has been found, the defaultValue is returned.

### has

bool has(
const std::string & name
) const;

Returns true if there is at least one name-value pair with the given name.

### operator =

NameValueCollection & operator = (
const NameValueCollection & nvc
);

Assigns the name-value pairs of another NameValueCollection to this one.

### operator =

NameValueCollection & operator = (
NameValueCollection && nvc
) noexcept;

Moves the name-value pairs of another NameValueCollection to this one.

### operator []

const std::string & operator[] (
const std::string & name
) const;

Returns the value of the (first) name-value pair with the given name.

Throws a NotFoundException if the name-value pair does not exist.

### set

void set(
const std::string & name,
const std::string & value
);

Sets the value of the (first) name-value pair with the given name.

### size

std::size_t size() const;

Returns the number of name-value pairs in the collection.

### swap

void swap(
NameValueCollection & nvc
) noexcept;

Swaps the NameValueCollection with another one.