std::unorde...iset::empty(3)

💅 std::unordered_multiset::empty

okay bestie, welcome to the <unordered_set> glow-up page 💖 this one lives in the C++ Standard Library and the star of the show is std::unordered_multiset::empty — yes the name is literally the same as the page title, we love a self-titled icon ✨

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✨ SYNOPSIS ✨

bool empty() const noexcept;                (since C++11)
                                            (until C++20)
[[nodiscard]] bool empty() const noexcept;  (since C++20)

so basically it checks if the container has no elements, i.e. whether begin() == end() 🎀 like, is your multiset giving empty-girl energy or not, that's the whole vibe check.

heads up: since C++20 it's got [[nodiscard]] on it — meaning if you call it and then just ignore the result, the compiler is gonna side-eye you 😭 don't do that, use the answer.

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🌸 PARAMETERS 🌸

(none) — not a single argument, she takes zero notes, zero input, purely vibes 🫶

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⭐ RETURN VALUE ⭐

• true if the container is empty 🎉
• false otherwise 💀

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🦋 COMPLEXITY 🦋

Constant. — as in, O(1), instant, no scrolling required, iconic behavior 👑

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🌈 EXAMPLE 🌈

the following code uses empty to check if a std::unordered_multiset<int> contains any elements:

// Run this code

#include <iostream>
#include <unordered_set>

int main()
{
    std::unordered_multiset<int> numbers;
    std::cout << std::boolalpha;
    std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n';

    numbers.insert(42);
    numbers.insert(19937);
    std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n';
}

🎀 Output

Initially, numbers.empty(): true
After adding elements, numbers.empty(): false

see how it flipped from true to false once we inserted 42 and 19937?? the way that she just knows 😭🔥 main character energy fr fr.

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👀 SEE ALSO

• size — returns the number of elements (public member function 🧚)
• empty (C++17) — checks whether the container is empty (function template ✨)

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and that's the whole page bestie, no cap, every last detail accounted for 💅

source/version + date: this lil masterpiece comes from http://cppreference.com, version 2024.06.10 — mwah, catch you on the next manpage 🫶💖🎀