std::erase_if (std::flat_set)
From cppreference.com
| Defined in header <flat_set>
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| template< class Key, class Compare, class KeyContainer, class Pred > |
(since C++23) | |
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.
Key must be MoveAssignable. Otherwise, the behavior is undefined.
Parameters
| c | - | container adaptor from which to erase |
| pred | - | predicate that returns true if the element should be erased |
Return value
The number of erased elements.
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.
Example
Run this code
#include <iostream> #include <flat_set> void println(auto rem, auto const& 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 = [](auto const& 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.See also
| removes elements satisfying specific criteria (function template) | |
| (C++20)(C++20) |
removes elements satisfying specific criteria (niebloid) |