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std::queue< _Tp, _Sequence >(3) Library Functions Manual std::queue< _Tp, _Sequence >(3)

NAME

std::queue< _Tp, _Sequence > - A standard container giving FIFO behavior.

SYNOPSIS

Public Types


typedef _Sequence::const_reference const_reference
typedef _Sequence container_type
typedef _Sequence::reference reference
typedef _Sequence::size_type size_type
typedef _Sequence::value_type value_type

Public Member Functions


template<typename _Seq = _Sequence, typename _Requires = typename enable_if<is_default_constructible<_Seq>::value>::type> queue ()
Default constructor creates no elements. queue (_Sequence &&__c)
template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (_Sequence &&__c, const _Alloc &__a)
template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (const _Alloc &__a)
queue (const _Sequence &__c)
template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (const _Sequence &__c, const _Alloc &__a)
template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (const queue &__q, const _Alloc &__a)
template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (queue &&__q, const _Alloc &__a)
reference back ()
const_reference back () const
template<typename... _Args> decltype(auto) emplace (_Args &&... __args)
bool empty () const
reference front ()
const_reference front () const
void pop ()
Removes first element. void push (const value_type &__x)
Add data to the end of the queue. void push (value_type &&__x)
size_type size () const
void swap (queue &__q) noexcept(__is_nothrow_swappable< _Sequence >::value)

Protected Attributes


_Sequence c
c is the underlying container.

Friends


template<typename _Tp1 , typename _Seq1 > bool operator< (const queue< _Tp1, _Seq1 > &, const queue< _Tp1, _Seq1 > &)
template<typename _Tp1 , typename _Seq1 > bool operator== (const queue< _Tp1, _Seq1 > &, const queue< _Tp1, _Seq1 > &)

Detailed Description

template<typename _Tp, typename _Sequence = deque<_Tp>>

class std::queue< _Tp, _Sequence >" A standard container giving FIFO behavior.

Template Parameters

_Tp Type of element.
_Sequence Type of underlying sequence, defaults to deque<_Tp>.

Meets many of the requirements of a container, but does not define anything to do with iterators. Very few of the other standard container interfaces are defined.

This is not a true container, but an adaptor. It holds another container, and provides a wrapper interface to that container. The wrapper is what enforces strict first-in-first-out queue behavior.

The second template parameter defines the type of the underlying sequence/container. It defaults to std::deque, but it can be any type that supports front, back, push_back, and pop_front, such as std::list or an appropriate user-defined type.

Members not found in normal containers are container_type, which is a typedef for the second Sequence parameter, and push and pop, which are standard queue/FIFO operations.

Constructor & Destructor Documentation

template<typename _Tp , typename _Sequence = deque<_Tp>> template<typename _Seq = _Sequence, typename _Requires = typename enable_if<is_default_constructible<_Seq>::value>::type> std::queue< _Tp, _Sequence >::queue () [inline]

Default constructor creates no elements.

Member Function Documentation

template<typename _Tp , typename _Sequence = deque<_Tp>> reference std::queue< _Tp, _Sequence >::back () [inline]

Returns a read/write reference to the data at the last element of the queue.

template<typename _Tp , typename _Sequence = deque<_Tp>> const_reference std::queue< _Tp, _Sequence >::back () const [inline]

Returns a read-only (constant) reference to the data at the last element of the queue.

template<typename _Tp , typename _Sequence = deque<_Tp>> bool std::queue< _Tp, _Sequence >::empty () const [inline]

Returns true if the queue is empty.

References std::queue< _Tp, _Sequence >::c.

template<typename _Tp , typename _Sequence = deque<_Tp>> reference std::queue< _Tp, _Sequence >::front () [inline]

Returns a read/write reference to the data at the first element of the queue.

template<typename _Tp , typename _Sequence = deque<_Tp>> const_reference std::queue< _Tp, _Sequence >::front () const [inline]

Returns a read-only (constant) reference to the data at the first element of the queue.

template<typename _Tp , typename _Sequence = deque<_Tp>> void std::queue< _Tp, _Sequence >::pop () [inline]

Removes first element. This is a typical queue operation. It shrinks the queue by one. The time complexity of the operation depends on the underlying sequence.

Note that no data is returned, and if the first element's data is needed, it should be retrieved before pop() is called.

template<typename _Tp , typename _Sequence = deque<_Tp>> void std::queue< _Tp, _Sequence >::push (const value_type & __x) [inline]

Add data to the end of the queue.

Parameters

__x Data to be added.

This is a typical queue operation. The function creates an element at the end of the queue and assigns the given data to it. The time complexity of the operation depends on the underlying sequence.

References std::queue< _Tp, _Sequence >::c.

template<typename _Tp , typename _Sequence = deque<_Tp>> size_type std::queue< _Tp, _Sequence >::size () const [inline]

Returns the number of elements in the queue.

References std::queue< _Tp, _Sequence >::c.

Member Data Documentation

template<typename _Tp , typename _Sequence = deque<_Tp>> _Sequence std::queue< _Tp, _Sequence >::c [protected]

c is the underlying container.

Referenced by std::queue< _Tp, _Sequence >::empty(), std::operator<(), std::operator==(), std::queue< _Tp, _Sequence >::push(), and std::queue< _Tp, _Sequence >::size().

Author

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Mon Dec 18 2023 libstdc++