std::unorde...ucket_count(3)

💅 std::unordered_map::max_bucket_count 💅

okay bestie so this page lives in the C++ Standard Library manual (you already knew that, you're iconic) — and today's main character is std::unordered_map::max_bucket_count 🎀

No cap, this one is a lil cutie. Let's get into it ✨

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🌸 NAME 🌸

std::unordered_map::max_bucket_count — like, literally std::unordered_map::max_bucket_count 💖

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🦋 Synopsis 🦋

The ✨vibe✨ is:

size_type max_bucket_count() const;  (since C++11)

So what it does is — it hands you back the maximum number of buckets the container can even hold, because of system or library implementation limitations. That's it, that's the whole personality 🫶

ngl "system or library implementation limitations" is doing a lot of heavy lifting there — it just means your computer / your stdlib says "bestie this is my ceiling" 💀

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💜 Parameters 💜

(none) — she takes nothing, she needs nothing, she is unbothered 👑

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⭐ Return value ⭐

The maximum number of buckets. That's the whole thing. Slay 🌈

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🧚 Complexity 🧚

Constant. Fast. Instant. No drama, no waiting, we love a low-effort queen 💅

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🍓 Example 🍓

Run this code, fr fr:

#include <iostream>
#include <unordered_map>

int main()
{
    struct Ha { std::size_t operator()(long x) const { return std::hash<long>{}(x); }; };

    auto c1 = std::unordered_map<char, long>{};
    auto c2 = std::unordered_map<long, long>{};
    auto c3 = std::unordered_map<long, long, std::hash<int>>{};
    auto c4 = std::unordered_map<long, long, Ha>{};

    std::cout
        << "Max bucket count of\n" << std::hex << std::showbase
        << "c1: " << c1.max_bucket_count() << '\n'
        << "c2: " << c2.max_bucket_count() << '\n'
        << "c3: " << c3.max_bucket_count() << '\n'
        << "c4: " << c4.max_bucket_count() << '\n'
        ;
}

Like — four whole maps, four different template setups, all just flexing their bucket ceilings 😭 and yes, we're printing in hex with std::showbase because we're classy like that 💅

Possible output:

Max bucket count of
c1: 0xfffffffffffffff
c2: 0xfffffffffffffff
c3: 0xfffffffffffffff
c4: 0xaaaaaaaaaaaaaaa

Not c4 pulling up with a completely different number and zero explanation 😭 — anyway, that's what you get, taste the rainbow 🌈

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🔥 See also 🔥

• bucket_count — returns the number of buckets (public member function) — like her chiller, more chillaxed cousin, iykyk 👑

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okay that's the whole page, love u, go write some hash maps 💖 — this one was published on cppreference over at http://cppreference.com, dated 2024.06.10, and it's the std::unorde...ucket_count(3) page in the C++ Standard Libary manual. mwah, see u in the next one 🎀✨🦋