std::experi...if(std::map)(3)

okay so this is the std::experi...if(std::map)(3) page from the C++ Standard Libary manual 💖 and it's literally all about erasing stuff from a std::map with a predicate. iconic behavior, no cap.

💖 NAME

std::experimental::erase_if(std::map) - std::experimental::erase_if(std::map)

(yes bestie, the NAME line repeats itself twice — we love a consistent queen 💅)

🌸 Synopsis

Defined in header <experimental/map>.

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

It erases all elements that satisfy the predicate pred from the container. Equivalent to:

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

🎀 Parameters

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

⚡ Complexity

Linear. periodt.

🧚 Example

// Run this code

#include <experimental/map>
#include <iostream>

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

int main()
{
    std::map<int, char> data{{1, 'a'},{2, 'b'},{3, 'c'},{4, 'd'},
                             {5, 'e'},{4, 'f'},{5, 'g'},{5, 'g'}};
    std::cout << "Original:\n" << data << '\n';
    std::experimental::erase_if(data, [](const auto& item)
    {
        return (item.first & 1) == 1;
    });
    std::cout << "Erase items with odd keys:\n" << data << '\n';
}

🍓 Output

Original:
{{1, a}{2, b}{3, c}{4, d}{5, e}}
Erase items with odd keys:
{{2, b}{4, d}}

👑 See also

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

🏷️ Category

• Noindexed pages

💖 that's the whole page, bestie! source/version: http://cppreference.com; date: 2024.06.10; page: std::experi...if(std::map)(3). bye, go erase with confidence 🫶