std::erase_if (std::flat_set)
From cppreference.com
| Defined in header <flat_set>
|
||
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) | |
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.