std::set::empty(3)

💖 NAME 💖

std::set::empty - std::set::empty, bestie — yes, that's the whole name line, and it's giving “the function is literally named after what it checks.” This page is std::set::empty(3) from the C++ Standard Libary manual (spelled exactly like that in the header, no cap 👀).

---

✨ Synopsis ✨

Okay so here are the exact signatures, era labels and all — keep that lone (until C++20) line, it's part of the package 🎀:

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

It checks if the container has no elements, i.e. whether begin() == end().

---

🌸 Parameters 🌸

(none) — zero parameters, zero stress, it is literally not asking you for anything 🫶.

---

🦋 Return value 🦋

• true if the container is empty
• false otherwise

That's it. Iconic behavior, no notes 💅.

---

⭐ Complexity ⭐

Constant. Lowkey the easiest complexity reveal ever.

---

🎀 Example 🎀

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

// Run this code

#include <iostream>
#include <set>

int main()
{
    std::set<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

Not the numbers 42 and 19937 doing main character energy in the example 😭✨.

---

💅 See also 💅

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

---

mwah 💋 source/version/date sign-off: http://cppreference.com · 2024.06.10 · std::set::empty(3) — bye bestie, go check those containers 🫶💖