CODEWITHSUNDEEP
c++oopstlqueuepriority-queue
R_M_R
R_M_R

Reputation: 53

"error: no matching function for call to 'std::priority_queue<int>::priority_queue(int)' priority_queue<int> pqueue(4); "

I tried to allocate memory to the priority_queue using the constructor, but getting the below error:

No matching constructor for initialization of 'priority_queue pq(3)'

why this is not working in priority_queue but working correctly in vectors?

#include <iostream> 
#include <queue> 
using namespace std; 

int main() 
{ 

priority_queue<int> pqueue(4); 
pqueue.push(3); 
pqueue.push(5); 
pqueue.push(1); 
pqueue.push(2); 

}

Upvotes: 0

Views: 2147

Answers (2)

mrazimi
mrazimi

Reputation: 337

related question

std::priority_queue doesn't have such constructor, but the below code implements what you want:

std::vector<int> temporary_container(4);

std::priority_queue<int, std::vector<int>> pqueue (comparator, std::move(container));

Also if you want not to change the size of queue and only reserve memory, you can do it like below:

std::vector<int> temporary_container;
temporary_container.reserve(4);

std::priority_queue<int, std::vector<int>> pqueue (comparator, std::move(container));

Using this ways, you should define your comparator and pass it to the constructor.

Upvotes: 2

darune
darune

Reputation: 10972

A std::priority_queue has a restrictive interface, isn't the same thing as a std::vector and doesn't have that constructor.

See https://en.cppreference.com/w/cpp/container/priority_queue/priority_queue for constructor summary.

To fix the compile error, you may just do instead:

priority_queue<int> pqueue{};

Upvotes: 0

Related Questions