std::queue man page

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

queue (const _Sequence &__c)
Default constructor creates no elements.
queue (_Sequence &&__c=_Sequence())

template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (const _Alloc &__a)

template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (const _Sequence &__c, const _Alloc &__a)

template<typename _Alloc , typename _Requires = _Uses<_Alloc>> queue (_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> void 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< _Tp >::value)

Protected Attributes

_Sequence c

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.

Definition at line 96 of file stl_queue.h.

Constructor & Destructor Documentation

template<typename _Tp, typename _Sequence = deque<_Tp>> std::queue< _Tp, _Sequence >::queue (const _Sequence & __c) [inline], [explicit]

Default constructor creates no elements.

Definition at line 147 of file stl_queue.h.

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

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.

Definition at line 215 of file stl_queue.h.

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.

Definition at line 226 of file stl_queue.h.

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

Returns true if the queue is empty.

Definition at line 180 of file stl_queue.h.

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.

Definition at line 193 of file stl_queue.h.

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.

Definition at line 204 of file stl_queue.h.

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.

Definition at line 268 of file stl_queue.h.

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.

Definition at line 242 of file stl_queue.h.

Referenced by std::priority_queue< _Tp, _Sequence, _Compare >::push().

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

Returns the number of elements in the queue.

Definition at line 185 of file stl_queue.h.

Member Data Documentation

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

'c' is the underlying container. Maintainers wondering why this isn't uglified as per style guidelines should note that this name is specified in the standard, [23.2.3.1]. (Why? Presumably for the same reason that it's protected instead of private: to allow derivation. But none of the other containers allow for derivation. Odd.)

Definition at line 135 of file stl_queue.h.

Referenced by std::operator<(), std::operator==(), std::priority_queue< _Tp, _Sequence, _Compare >::priority_queue(), and std::queue< _Tp, _Sequence >::queue().

Author

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Fri Sep 16 2016 libstdc++