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std::priori...iority_queue(3) C++ Standard Libarystd::priori...iority_queue(3) NAME std::priority_queue::priority_queue - std::priority_queue::prior- ity_queue Synopsis priority_queue() : priority_queue(Compare(), (1) (since Container()) { } C++11) explicit priority_queue( const Compare& compare ) (2) (since : priority_queue(compare, Container()) { } C++11) explicit priority_queue( const Compare& compare = (until Compare(), C++11) const Container& cont = Container() ); priority_queue( const Compare& compare, const Container& (since cont ); C++11) priority_queue( const Compare& compare, Container&& cont (4) (since ); C++11) priority_queue( const priority_queue& other ); (5) priority_queue( priority_queue&& other ); (6) (since C++11) template< class InputIt > (since priority_queue( InputIt first, InputIt last, (7) C++11) const Compare& compare = Compare() ); template< class InputIt > priority_queue( InputIt first, InputIt last, (until const Compare& compare = Compare(), C++11) const Container& cont = Container() ); template< class InputIt > (since priority_queue( InputIt first, InputIt last, C++11) const Compare& compare, const Container& cont ); template< class InputIt > (since priority_queue( InputIt first, InputIt last, (9) C++11) const Compare& compare, Container&& cont ); template< class Alloc > (10) (since explicit priority_queue( const Alloc& alloc ); C++11) template< class Alloc > (since priority_queue( const Compare& compare, const Alloc& (11) C++11) alloc ); template< class Alloc > (3) priority_queue( const Compare& compare, const Container& (12) (since cont, C++11) const Alloc& alloc ); template< class Alloc > priority_queue( const Compare& compare, Container&& (8) (13) (since cont, C++11) const Alloc& alloc ); template< class Alloc > (since priority_queue( const priority_queue& other, const (14) C++11) Alloc& alloc ); template< class Alloc > (since priority_queue( priority_queue&& other, const Alloc& (15) C++11) alloc ); template< class InputIt, class Alloc > (since priority_queue( InputIt first, InputIt last, const (16) C++11) Alloc& alloc ); template< class InputIt, class Alloc > priority_queue( InputIt first, InputIt last, const (17) (since Compare& compare, C++11) const Alloc& alloc ); template< class InputIt, class Alloc > priority_queue( InputIt first, InputIt last, const (18) (since Compare& compare, C++11) const Container& cont, const Alloc& alloc ); template< class InputIt, class Alloc > priority_queue( InputIt first, InputIt last, const (19) (since Compare& compare, C++11) Container&& cont, const Alloc& alloc ); Constructs new underlying container of the container adaptor from a variety of data sources. 1) Default constructor. Value-initializes the comparator and the un- derlying container. 2) Copy-constructs the comparison functor comp with the contents of compare. Value-initializes the underlying container c. 3) 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) 4) Move-constructs the underlying container c with std::move(cont). Copy-constructs the comparison functor comp with compare. Calls std::make_heap(c.be- gin(), c.end(), comp). 5) Copy constructor. The underlying container is copy-constructed with other.c. The comparison functor is copy-constructed with other.comp. (implicitly declared) 6) Move constructor. The underlying container is constructed with std::move(other.c).The comparison functor is constructed with std::move(other.comp). (implicitly declared) 7-9) Iterator-pair constructors. These overloads participate in overload resolution only if InputIt satisfies LegacyInputIterator. 7) Constructs c as if by c(first, last) and comp from compare. Then calls std::make_heap(c.begin(), c.end(), comp);. 8) 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);. 9) Move-constructs c from std::move(cont) and copy-constructs comp from compare. Then calls c.insert(c.end(), first, last);, and then calls std::make_heap(c.begin(), c.end(), comp);. 10-15) Allocator-extended constructors. These overloads participate in overload resolution only if std::uses_allocator<container_type, Alloc>::value is true, that is, if the underlying container is an allocator-aware container (true for all standard library containers). 10) Constructs the underlying container using alloc as allocator. Effectively calls c(alloc). comp is value-initialized. 11) Constructs the underlying container using alloc as allocator. Effectively calls c(alloc). Copy-constructs comp from compare. 12) Constructs the underlying container with the contents of cont and using alloc as allocator, as if by c(cont, alloc). Copy-constructs comp from com- pare. Then calls std::make_heap(c.begin(), c.end(), comp). 13) Constructs the underlying container with the contents of cont using move semantics while using alloc as allocator, as if by c(std::move(cont), alloc). Copy-constructs comp from compare. Then calls std::make_heap(c.be- gin(), c.end(), comp). 14) Constructs the underlying container with the contents of other.c and using alloc as allocator. Effectively calls c(other.c, alloc). Copy-constructs comp from other.comp. 15) Constructs the underlying container 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. 16-19) Allocator-extended iterator-pair constructors. Same as (7-9), except that alloc is used for constructing the underlying container. These over- loads participate in overload resolution only if std::uses_allocator<container_type, Alloc>::value is true and InputIt satisfies LegacyInputIterator. Note that how an implementation checks whether a type satisfies LegacyInputIterator is unspecified, except that integral types are required to be re- jected. Parameters alloc - allocator to use for all memory alloca- tions 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 ini- tialize the underlying container compare - the comparison function object to ini- tialize the underlying comparison functor first, last - range of elements to initialize with Type requirements - Alloc must meet the requirements of Allocator. - Container must meet the requirements of Container. The allocator-ex- tended constructors are only defined if Container meets the requirements of AllocatorAwareContainer - InputIt must meet the requirements of LegacyInputIterator. Complexity 1-2) Constant. 3,5) \(\scriptsize \mathcal{O}{(N)}\)O(N) comparisons and \(\script- size \mathcal{O}{(N)}\)O(N) calls to the constructor of value_type, where \(\scriptsize N\)N is cont.size(). 4) \(\scriptsize \mathcal{O}{(N)}\)O(N) comparisons, where \(\scriptsize N\)N is cont.size(). 6) Constant. 7,16-17) \(\scriptsize \mathcal{O}{(M)}\)O(M) comparisons, where \(\scriptsize M\)M is std::distance(first, last). 8,18) \(\scriptsize \mathcal{O}{(N+M)}\)O(N+M) comparisons and \(\scriptsize \mathcal{O}{(N)}\)O(N) calls to the constructor of value_type, where \(\scriptsize N\)N and \(\scriptsize M\)M are cont.size() and std::distance(first, last) respectively. 9) \(\scriptsize \mathcal{O}{(N)}\)O(N) comparisons, where \(\scriptsize N\)N is cont.size() + std::distance(first, last). 10-11) Constant. 12) \(\scriptsize \mathcal{O}{(N)}\)O(N) comparisons and \(\script- size \mathcal{O}{(N)}\)O(N) calls to the constructor of value_type, where \(\scriptsize N\)N is cont.size(). 13) \(\scriptsize \mathcal{O}{(N)}\)O(N) comparisons, where \(\scriptsize N\)N is cont.size(). 14) Linear in size of other. 15) Constant if Alloc compares equal to the allocator of other. Lin- ear in size of other otherwise. 19) \(\scriptsize \mathcal{O}{(N+M)}\)O(N+M) comparisons and possi- bly present \(\scriptsize \mathcal{O}{(N)}\)O(N) calls to the constructor of value_type (present if Alloc does not compare equal to the allocator of other), where \(\scriptsize N\)N and \(\scriptsize M\)M are cont.size() and std::distance(first, last) respectively. Example // Run this code #include <complex> #include <functional> #include <iostream> #include <queue> #include <vector> int main() { std::priority_queue<int> pq1; pq1.push(5); std::cout << "pq1.size() = " << pq1.size() << '\n'; std::priority_queue<int> pq2 {pq1}; std::cout << "pq2.size() = " << pq2.size() << '\n'; std::vector<int> vec {3, 1, 4, 1, 5}; std::priority_queue<int> pq3 {std::less<int>(), vec}; std::cout << "pq3.size() = " << pq3.size() << '\n'; for (std::cout << "pq3 : "; !pq3.empty(); pq3.pop()) { std::cout << pq3.top() << ' '; } std::cout << '\n'; // Demo With Custom Comparator: using my_value_t = std::complex<double>; using my_container_t = std::vector<my_value_t>; auto my_comp = [](const my_value_t& z1, const my_value_t& z2) { return z2.real() < z1.real(); }; std::priority_queue<my_value_t, my_container_t, decltype(my_comp)> pq4 {my_comp}; using namespace std::complex_literals; pq4.push(5.0 + 1i); pq4.push(3.0 + 2i); pq4.push(7.0 + 3i); for (; !pq4.empty(); pq4.pop()) { const auto& z = pq4.top(); std::cout << "pq4.top() = " << z << '\n'; } } Output: pq1.size() = 1 pq2.size() = 1 pq3.size() = 5 pq3 : 5 4 3 1 1 pq4.top() = (3,2) pq4.top() = (5,1) pq4.top() = (7,3) Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Cor- rect behavior P0935R0 C++11 default constructor and constructor (4) made im- plicit were explicit LWG 3506 C++11 allocator-extended iterator-pair added constructors were missing LWG 3522 C++11 constraints on iterator-pair added constructors were missing LWG 3529 C++11 construction from a pair of iterators con- structs the container called insert from them See also operator= assigns values to the container adaptor (public member function) http://cppreference.com 2022.07.31 std::priori...iority_queue(3)
NAME | Synopsis | Parameters | Type requirements | Complexity | Example | Output: | See also
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