A priority queue is a dynamically resizing container adopter in the C++ Standard Library. Elements in a priority queue are arranged in non-decreasing order such that the first element is always the greatest element in the queue. The priority_queue::empty() is a method available in the STL which returns whether the priority queue is empty i.e. whether its size is zero.
Syntax:
priorityq_name.empty();
Parameter: The priority_queue::empty() does not accept any parameter
Return value: true if the size is 0, false otherwise.
Example of priority_queue::empty() method
#include <iostream>>
#include <queue>
using namespace std;
void check(priority_queue <int> q) //helper function to print whether empty queue or not
{
if(q.empty())
{
cout<<"true";
}
else
{
cout<<"false";
}
}
int main ()
{
priority_queue<int> q1;
q1.push(10);
q1.push(20);
q1.push(40);
q1.push(30);
q1.push(50);
cout<<"Q1 is empty? ";
check(q1);
cout<<endl;
priority_queue<int> q2;
cout<<"Q2 is empty? ";
check(q2);
return 0;
}
Output:
Q1 is empty? false Q2 is empty? true
