Namespaces
Variants
Views
Actions

std::experimental::erase_if (std::multimap)

From cppreference.com
Defined in header <experimental/map>
template< class Key, class T, class Compare, class Alloc, class Pred >
void erase_if(std::multimap<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;
  }
}

Contents

[edit] Parameters

c - container from which to erase
pred - predicate that determines which elements should be erased

[edit] Complexity

Linear.

[edit] Example

#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::multimap<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}{4, f}{5, e}{5, g}{5, g}}
Erase items with odd keys:
{{2, b}{4, d}{4, f}}

[edit] See also

removes elements satisfying specific criteria
(function template) [edit]