std::experi...d_multiset)(3)

✨ NAME ✨

okay so this page is titled std::experi...d_multiset)(3), and it’s from the C++ Standard Libary manual (their spelling, not mine 😭). the actual name is std::experimental::erase_if(std::unordered_multiset) — and yep, the NAME line says it twice, so here it is twice, bestie: std::experimental::erase_if(std::unordered_multiset) - std::experimental::erase_if(std::unordered_multiset). periodt 💅

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🌸 Synopsis 🌸

Defined in header <experimental/unordered_set>

this is the signature, and it’s tagged (library fundamentals TS v2):

template< class Key, class Hash, class KeyEqual, class Alloc, class Pred >
void erase_if( std::unordered_multiset<Key, Hash, KeyEqual, Alloc>& c, Pred pred );

it erases all elements that satisfy the predicate pred from the container. equivalent to this little loop right here:

for (auto i = c.begin(), last = c.end(); i != last;)
{
    if (pred(*i))
        i = c.erase(i);
    else
        ++i;
}

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💖 Parameters 💖

• c — container from which to erase 🫶
• pred — predicate that determines which elements should be erased ✨

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🔥 Complexity 🔥

Linear. that’s it, that’s the whole vibe. no cap. 🌈

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🎀 Example 🎀

// Run this code

#include <experimental/unordered_set>
#include <iostream>

template<typename Os, typename Container>
inline Os& operator<<(Os& os, Container const& container)
{
    os << "{ ";
    for (const auto& item : container)
        os << item << ' ';
    return os << '}';
}

int main()
{
    std::unordered_multiset<int> data{3, 3, 4, 5, 5, 6, 6, 7, 2, 1, 0};
    std::cout << "Original:\n" << data << '\n';
    auto divisible_by_3 = [](auto const& x) { return (x % 3) == 0; };
    std::experimental::erase_if(data, divisible_by_3);
    std::cout << "Erase all items divisible by 3:\n" << data << '\n';
}

🌈 Possible output 🌈

Original:
{ 0 1 2 7 6 6 5 5 4 3 3 }
Erase all items divisible by 3:
{ 1 2 7 5 5 4 }

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🦋 See also 🦋

• remove — removes elements satisfying specific criteria
• remove_if (function template)

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🏷️ Category 🏷️

• * Noindexed pages

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mwah 💋 — source/version: http://cppreference.com, date: 2024.06.10 ✨