home | help 
std::priority_queue::top(3)    C++ Standard Libary   std::priority_queue::top(3)

NAME
     std::priority_queue::top - std::priority_queue::top

Synopsis
	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.

Parameters
	(none)

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

Complexity
	Constant.

Example
     // Run this code

      #include <iostream>
      #include <queue>

      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<Event> 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'}

See also
	pop removes the top element
	    (public member function)

http://cppreference.com 	   2024.06.10	     std::priority_queue::top(3)
home | help