std::experi...::multiset)(3)

Hey bestie 💖 this is the std::experi...::multiset)(3) page from the C++ Standard Libary manual — yes, that's the manual name, typo and all — and we're about to make std::experimental::erase_if(std::multiset) make sense, fr fr.

💖 NAME 💖

std::experimental::erase_if(std::multiset) - std::experimental::erase_if(std::multiset)

✨ Synopsis ✨

Okay so first things first: this lives in the header <experimental/set>, and it's the (library fundamentals TS v2) version. Here's the signature, copied exactly so you can trust it:

template< class Key, class Compare, class Alloc, class
Pred >                                                  (library
fundamentals TS v2)
void erase_if( std::multiset<Key, Compare, Alloc>& c,
Pred pred );

What it does: it erases every single element that satisfies the predicate pred from the container. Equivalent to this exact loop, bestie:

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

🎀 Parameters 🎀

• c — the container from which to erase, aka the multiset you're cleaning up
• pred — the predicate that determines which elements should be erased

🔥 Complexity 🔥

Linear. One clean linear pass, no cap.

🧚 Example 🧚

Run this code, bestie — it's giving "watch me erase every divisible-by-3 element" energy:

// Run this code

#include <experimental/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::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';
}

🌈 Output 🌈

It prints exactly this, periodt:

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

👑 See also 👑

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

💀 Category 💀

• Noindexed pages

🫶 That's the whole page, bestie. Source: http://cppreference.com · version/date: 2024.06.10 · page: std::experi...::multiset)(3). Mwah 💋