std::erase_if (std::multiset)
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Defined in header
<set>
template< class Key, class Compare, class Alloc,
(since C++20) class Pred >
std::multiset <Key, Compare, Alloc>::size_type
erase_if( std::multiset <Key, Compare, Alloc>& c,
(constexpr since C++26)
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();
[edit] Parameters
c
-
container 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
Linear.
[edit] Example
Run this code
#include <iostream> #include <set> 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::multiset 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, 3, 4, 5, 5, 6, 6, 7}
Erase all items divisible by 3:
{1, 2, 4, 5, 5, 7}
5 items erased.