std::multiset::empty(3)

💅 NAME 💅

std::multiset::empty — bestie, it literally just tells you if your multiset is empty, that's it, that's the whole vibe ✨

This one lives in the C++ Standard Library man pages (std::multiset::empty(3)), so you already know it's giving iconic container energy 👑

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✨ Synopsis ✨

Watch the glow-up across the standards, because this signature has been through some eras 🦋

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

Ok so what does it actually do? It checks if the container has no elements, i.e. whether begin() == end(). That's the whole check, no cap 😌

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🎀 Parameters 🎀

(none)

Literally nothing. It takes zero arguments. It's a main character that needs no input 💅

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🌸 Return value 🌸

true if the container is empty, false otherwise.

Simple as that, bestie. Binary. Iconic. Periodt 🫶

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🦋 Complexity 🦋

Constant.

Constant!! It's O(1)! It does not care how big your multiset is, it's answering instantly, no thoughts head empty fr fr ⚡

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💖 Example 💖

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

// Run this code

#include <iostream>
#include <set>

int main()
{
    std::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';
}

Not me getting emotional over a multiset going from empty to having two whole elements in it 😭💀

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⭐ Output ⭐

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

Look at it. Look at the character development. Starts empty, ends full. We love a growth arc 🌈

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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)

💡 Quick vibe check: those two emptys are not the same thing — one is the member function you're reading about right now, and the other is the C++17 function template. Don't mix them up bestie 🙈

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and that's the whole page, you ate that 💅

Source and version: http://cppreference.com, 2024.06.10 — and the page you just read was std::multiset::empty(3). Now go forth and check your containers with confidence, bestie 🍓🧚💜