std::priority_queue::top(3)

✨ NAME ✨

okay so this is std::priority_queue::top(3), straight from the C++ Standard Libary man pages — yes bestie, that’s the spelling in the header, we’re not fixing it, it’s iconic 💅. And this page is all about the top() member of std::priority_queue. Obsessed.

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🎀 Synopsis 🎀

const_reference top() const;

This one returns a reference to the top element in the priority queue. That element is the one that will be removed on a call to pop(). And if the default comparison function is used, the returned element is also the greatest among the elements in the queue. periodt. 💖

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🌸 Parameters 🌸

• there are none. Literally (none), bestie. Not a single argument. 🫶

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🦋 Return value 🦋

A reference to the top element, as if obtained by a call to c.front(). That’s the whole return value, no cap. ✨

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⭐ Complexity ⭐

Constant. That’s the vibe. 🌈

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🔥 Example 🔥

Run this code, bestie:

// 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'}

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🌈 See also 🌈

• pop — removes the top element (public member function). That’s the one, bestie. 🫶

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Source/version/date cuteness: this page is from http://cppreference.com, version/date 2024.06.10, and it’s std::priority_queue::top(3). Byeee, go call top() responsibly 💖✨