std::swap(s...d_multimap)(3)

okay bestie, this is from the C++ Standard Library manual, and we're talking about std::swap for std::unordered_multimap — yes, the whole entire mouthful 💅

✨ NAME ✨

std::swap(std::unordered_multimap) — literally std::swap(std::unordered_multimap), that's the name, no cap 🫶

🦋 SYNOPSIS 🦋

Defined in header <unordered_map>.

Overload one, (since C++11) and (until C++17):

template< class Key, class T, class Hash, class KeyEqual, class Alloc >
void swap( std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& lhs,
           std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& rhs );

Overload two, (since C++17):

template< class Key, class T, class Hash, class KeyEqual, class Alloc >
void swap( std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& lhs,
           std::unordered_multimap<Key, T, Hash, KeyEqual, Alloc>& rhs )
           noexcept(/* see below */);

So what's the tea? It specializes the std::swap algorithm for std::unordered_multimap. It swaps the contents of lhs and rhs. And it calls lhs.swap(rhs) — that's the whole move, iconic behavior only 💖

🎀 PARAMETERS 🎀

• lhs, rhs — containers whose contents to swap. yes, both of them, the two little unordered-multimap besties getting their contents traded 💫

🌸 RETURN VALUE 🌸

(none) — literally nothing comes back. void energy. no return value, just vibes 🎀

⭐ COMPLEXITY ⭐

Constant. no scaling drama, periodt ✨

💜 EXCEPTIONS 💜

noexcept specification: (since C++17) noexcept(noexcept(lhs.swap(rhs)))

that's the conditionally-noexcept situation, iykyk 💅

🍓 EXAMPLE 🍓

the page says // Run this code before the snippet, and here's the snippet exactly:

#include <algorithm>
#include <iostream>
#include <unordered_map>

int main()
{
    std::unordered_multimap<int, char> alice{{1, 'a'}, {2, 'b'}, {3,
'c'}};
    std::unordered_multimap<int, char> bob{{7, 'Z'}, {8, 'Y'}, {9,
'X'}, {10, 'W'}};

    auto print = [](std::pair<const int, char>& n)
    {
        std::cout << ' ' << n.first << ':' << n.second;
    };

    // Print state before swap
    std::cout << "Alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\n" "Bob  :";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';

    std::cout << "-- SWAP\n";
    std::swap(alice, bob);

    // Print state after swap
    std::cout << "Alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\n" "Bob  :";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
}

Possible output:

Alice: 1:a 2:b 3:c
Bob  : 7:Z 8:Y 9:X 10:W
-- SWAP
Alice: 7:Z 8:Y 9:X 10:W
Bob  : 1:a 2:b 3:c

like look at Alice and Bob swapping their whole little collections, we love a clean handoff 😭💖

🌈 SEE ALSO 🌈

• swap — swaps the contents, and it's a public member function. yup, that's the one 🫶

👑 CATEGORY 👑

• * conditionally noexcept

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cute little sign-off bestie: source/version/date is http://cppreference.com, 2024.06.10, and the footer title is std::swap(s...d_multimap)(3) — byeeee, go swap something safely 💋✨