std::erase_if (std::flat_set) - cppreference.com (original) (raw)
| | | | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | ------------------------------------- | | template< class Key, class Compare, class KeyContainer, class Pred > std::flat_set<Key, Compare, KeyContainer>::size_type erase_if( std::flat_set<Key, Compare, KeyContainer>& c, Pred pred ); | | (since C++23) (constexpr since C++26) |
Erases all elements that satisfy the predicate pred from c.
The predicate pred is satisfied if the expression bool(pred(std::as_const(e))) is true, where e is some element in c.
If Key is not MoveAssignable, the behavior is undefined.
Contents
[edit] Parameters
| c | - | container adaptor from which to erase |
|---|---|---|
| pred | - | predicate that returns true if the element should be erased |
[edit] Return value
The number of erased elements.
[edit] Complexity
Exactly c.size() applications of the predicate pred.
Exceptions
If erase_if throws, c remains in valid but unspecified (maybe empty) state.
Notes
The algorithm is stable, that is, the order of elements that are not deleted remains unchanged.
[edit] Example
#include #include void println(auto rem, const auto& container) { std::cout << rem << '{'; for (char sep[]{0, ' ', 0}; const auto& item : container) std::cout << sep << item, *sep = ','; std::cout << "}\n"; } int main() { std::flat_set data{3, 3, 4, 5, 5, 6, 6, 7, 2, 1, 0}; println("Original:\n", data); auto divisible_by_3 = [](const auto& x) { return (x % 3) == 0; }; const auto count = std::erase_if(data, divisible_by_3); println("Erase all items divisible by 3:\n", data); std::cout << count << " items erased.\n"; }
Output:
Original: {0, 1, 2, 3, 4, 5, 6, 7} Erase all items divisible by 3: {1, 2, 4, 5, 7} 3 items erased.