# std::experimental::erase_if (std::map)

From cppreference.com
< cpp‎ | experimental

Defined in header `<experimental/map>` |  |
template< class Key, class T, class Compare, class Alloc, class Pred > void erase_if( std::map<Key, T, Compare, Alloc>& c, Pred pred ); |  | (library fundamentals TS v2)

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.

### 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 remove_if | removes elements satisfying specific criteria (function template)

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