std::priority_queue(3)

NAME
std::priority_queue - A standard container automatically sorting its contents.

SYNOPSIS

#include <queue>

  Public Member Functions
priority_queue (const _Compare &__x=_Compare(), const _Sequence &__s=_Sequence())
Default constructor creates no elements.
template<typename _InputIterator> priority_queue (_InputIterator __first, _InputIterator __last, const _Compare &__x=_Compare(), const _Sequence &__s=_Sequence())
Builds a queue from a range.
bool empty () const
size_type size () const
const_reference top () const
void push (const value_type &__x)
Add data to the queue.
void pop ()
Removes first element.

Detailed Description

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> class std::priority_queue< _Tp, _Sequence, _Compare >
A standard container automatically sorting its contents. 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 sorting and first-in-first-out queue behavior. Very few of the standard container/sequence interface requirements are met (e.g., iterators).

The second template parameter defines the type of the underlying sequence/container. It defaults to std::vector, but it can be any type that supports front(), push_back, pop_back, and random-access iterators, such as std::deque or an appropriate user-defined type.

The third template parameter supplies the means of making priority comparisons. It defaults to less<value_type> but can be anything defining a strict weak ordering.

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

Note:
    No equality/comparison operators are provided for priority_queue.

    Sorting of the elements takes place as they are added to, and removed from, the priority_queue using the priority_queue's member functions. If you access the elements by other means, and change their data such that the sorting order would be different, the priority_queue will not re-sort the elements for you. (How could it know to do so?)

Definition at line 305 of file queue.

Constructor & Destructor Documentation

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> std::priority_queue< _Tp, _Sequence, _Compare >::priority_queue (const _Compare & __x = _Compare(), const _Sequence & __s = _Sequence()) [inline, explicit]

Default constructor creates no elements.

Definition at line 332 of file queue.

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> template<typename _InputIterator> std::priority_queue< _Tp, _Sequence, _Compare >::priority_queue (_InputIterator __first, _InputIterator __last, const _Compare & __x = _Compare(), const _Sequence & __s = _Sequence()) [inline]

Builds a queue from a range.Parameters:
    first An input iterator.
    last An input iterator.
    x A comparison functor describing a strict weak ordering.
    s An initial sequence with which to start.

Begins by copying s, inserting a copy of the elements from [first,last) into the copy of s, then ordering the copy according to x.

For more information on function objects, see the documentation on functor base classes.

Definition at line 352 of file queue.

Member Function Documentation

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> bool std::priority_queue< _Tp, _Sequence, _Compare >::empty () const [inline]

Returns true if the queue is empty.

Definition at line 365 of file queue.

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> void std::priority_queue< _Tp, _Sequence, _Compare >::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 412 of file queue.

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> void std::priority_queue< _Tp, _Sequence, _Compare >::push (const value_type & __x) [inline]

Add data to the queue.Parameters:
    x Data to be added.

This is a typical queue operation. The time complexity of the operation depends on the underlying sequence.

Definition at line 387 of file queue.

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> size_type std::priority_queue< _Tp, _Sequence, _Compare >::size () const [inline]

Returns the number of elements in the queue.

Definition at line 369 of file queue.

  template<typename _Tp, typename _Sequence = vector<_Tp>, typename _Compare = less<typename _Sequence::value_type>> const_reference std::priority_queue< _Tp, _Sequence, _Compare >::top () const [inline]

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

Definition at line 376 of file queue.

Author

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