Namespaces
Variants
Views
Actions

std::priority_queue::priority_queue

From cppreference.com
explicit priority_queue( const Compare& compare = Compare(),

                         const Container& cont = Container());

priority_queue( const Compare& compare, const Container& cont);
(1) (until C++11)

(since C++11)
explicit priority_queue( const Compare& compare = Compare(),
                         Container&& cont = Container());
(2) (since C++11)
priority_queue( const priority_queue& other );
(3)
priority_queue( priority_queue&& other );
(4) (since C++11)
template< class Allocator >
explicit priority_queue( const Allocator& alloc );
(5) (since C++11)
template< class Allocator >
priority_queue( const Compare& compare, const Allocator& alloc );
(6) (since C++11)
template< class Allocator >

priority_queue( const Compare& compare, const Container& cont,

                const Allocator& alloc );
(7) (since C++11)
template< class Allocator >

priority_queue( const Compare& compare, Container&& cont,

                const Allocator& alloc );
(8) (since C++11)
template< class Allocator >
priority_queue( const priority_queue& other, const Allocator& alloc );
(9) (since C++11)
template< class Allocator >
priority_queue( priority_queue&& other, const Allocator& alloc );
(10) (since C++11)
template< class InputIterator >

priority_queue( InputIterator first, InputIterator last,

                const Compare& compare, const Container& cont );
(11) (since C++11)
template< class InputIterator >

priority_queue(InputIterator first, InputIterator last,

               const Compare& compare = Compare(), Container&& cont = Container());
(12) (since C++11)

Constructs new underlying container of the container adaptor from a variety of data sources.

1) Copy-constructs the underlying container c with the contents of cont. Copy-constructs the comparison functor comp with the contents of compare. Calls std::make_heap(c.begin(), c.end(), comp). This is also the default constructor (until C++11)

2) Move-constructs the underlying container c with std::move(cont). Move-constructs the comparison functor comp with std::move(compare). Calls std::make_heap(c.begin(), c.end(), comp). This is also the default constructor (since C++11)

3) Copy constructor. The adaptor is copy-constructed with the contents of other.c. The comparison functor is constructed with std::move(other.comp). (implicitly declared)

4) Move constructor. The adaptor is constructed with std::move(other.c). The comparison functor is constructed with std::move(other.comp). (implicitly declared)

The constructors 5..10 are only defined if std::uses_allocator<container_type, Alloc>::value == true, that is, if the underlying container is an allocator-aware container (true for all standard library containers).

5) Constructs the underlying container using alloc as allocator. Effectively calls c(alloc). comp is value-initialized.

6) Constructs the underlying container using alloc as allocator. Effectively calls c(alloc). Copy-constructs comp from compare.

7) Constructs the underlying container with the contents of cont and using alloc as allocator. Effectively calls c(cont, alloc). Copy-constructs comp from compare.

8) Constructs the underlying container with the contents of cont using move semantics while utilising alloc as allocator. Effectively calls c(std::move(cont), alloc). Copy-constructs comp from compare.

9) Constructs the adaptor with the contents of other.c and using alloc as allocator. Effectively calls c(athor.c, alloc). Copy-constructs comp from other.comp.

10) Constructs the adaptor with the contents of other using move semantics while utilising alloc as allocator. Effectively calls c(std::move(other.c), alloc). Move-constructs comp from other.comp.

11) Copy-constructs c from cont and comp from compare. Then calls c.insert(c.end(), first, last);, and then calls std::make_heap(c.begin(), c.end(), comp);.

12) Move-constructs c from std::move(cont) and comp from std::move(compare). Then calls c.insert(c.end(), first, last);, and then calls std::make_heap(c.begin(), c.end(), comp);.

Contents

[edit] Parameters

alloc - allocator to use for all memory allocations of the underlying container
other - another container adaptor to be used as source to initialize the underlying container
cont - container to be used as source to initialize the underlying container
compare - the comparison function object to initialize the underlying comparison functor
first - InputIterator pointing at the beginning of the initialization sequence
last - InputIterator pointing one past the end of the initialization sequence

[edit] Complexity

1, 3, 5, 6, 8: linear in cont or other

2, 4, 7, 9: constant

[edit] Example

#include <queue>
#include <deque>
#include <iostream>
 
int main()
{
    std::priority_queue<int> c1;
    c1.push(5);
    std::cout << c1.size() << '\n';
 
    std::priority_queue<int> c2(c1);
    std::cout << c2.size() << '\n';
 
    std::deque<int> deq {3, 1, 4, 1, 5};
    std::priority_queue<int> c3(std::less<int>(),deq);
    std::cout << c3.size() << '\n';
}

Output:

1
1
5

[edit] See also

assigns values to the container adaptor
(public member function) [edit]