std::priority_queue<T,Container,Compare>::top - cppreference.com (original) (raw)

| const_reference top() const; | | | | ----------------------------- | | |

Returns reference to the top element in the priority queue. This element will be removed on a call to pop(). If default comparison function is used, the returned element is also the greatest among the elements in the queue.

[edit] Return value

Reference to the top element as if obtained by a call to c.front().

[edit] Complexity

Constant.

[edit] Example

#include #include   struct Event { int priority{}; char data{' '};   friend bool operator<(Event const& lhs, Event const& rhs) { return lhs.priority < rhs.priority; }   friend std::ostream& operator<<(std::ostream& os, Event const& e) { return os << '{' << e.priority << ", '" << e.data << "'}"; } };   int main() { std::priority_queue events;   std::cout << "Fill the events queue:\t";   for (auto const e : {Event{6,'L'}, {8,'I'}, {9,'S'}, {1,'T'}, {5,'E'}, {3,'N'}}) { std::cout << e << ' '; events.push(e); }   std::cout << "\nProcess events:\t\t";   for (; !events.empty(); events.pop()) { Event const& e = events.top(); std::cout << e << ' '; }   std::cout << '\n'; }

Output:

Fill the events queue: {6, 'L'} {8, 'I'} {9, 'S'} {1, 'T'} {5, 'E'} {3, 'N'} Process events: {9, 'S'} {8, 'I'} {6, 'L'} {5, 'E'} {3, 'N'} {1, 'T'}

[edit] See also

| | removes the top element (public member function) [edit] | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |