std::experimental::erase_if (std::unordered_map) - cppreference.com (original) (raw)
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Merged into ISO C++ The functionality described on this page was merged into the mainline ISO C++ standardas of 11/2018, see std::erase_if (since C++20) |
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| | | | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ---------------------------- | | template< class Key, class T, class Hash, class KeyEqual, class Alloc, class Pred > void erase_if( std::unordered_map<Key, T, Hash, KeyEqual, 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; }
[edit] Parameters
| c | - | container from which to erase |
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| pred | - | predicate that determines which elements should be erased |
[edit] Complexity
Linear.
[edit] Example
#include <experimental/unordered_map> #include 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::unordered_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'; }
Possible output:
Original: {{5, e}{4, d}{3, c}{2, b}{1, a}} Erase items with odd keys: {{4, d}{2, b}}