std::erase_if (std::set)
From cppreference.com
| Defined in header <set>
|
||
template< class Key, class Compare, class Alloc,
class Pred >
std::set<Key, Compare, Alloc>::size_type
erase_if( std::set<Key, Compare, Alloc>& c,
Pred pred );
|
(since C++20) | |
Erases all elements that satisfy the predicate pred from c.
Equivalent to
auto old_size = c.size();
for (auto first = c.begin(), last = c.end(); first != last;)
{
if (pred(*first))
first = c.erase(first);
else
++first;
}
return old_size - c.size();
Parameters
| c | - | container from which to erase |
| pred | - | predicate that returns true if the element should be erased
|
Return value
The number of erased elements.
Complexity
Linear.
Example
Run this code
#include <iostream>
#include <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::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 (algorithm function object) |
