std::experimental::erase_if (std::unordered_map)
From cppreference.com
< cpp | experimental
| Defined in header <experimental/unordered_map>
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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; }
Parameters
| c | - | container from which to erase |
| pred | - | predicate that determines which elements should be erased |
Complexity
Linear.
Example
Run this code
#include <experimental/unordered_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::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}}See also
| removes elements satisfying specific criteria (function template) |