std::erase_if (std::unordered_multiset)
From cppreference.com
< cpp | container | unordered multiset
Defined in header <unordered_set>
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template< class Key, class Hash, class KeyEqual, class Alloc, class 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();
Contents |
[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 <unordered_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::unordered_multiset 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"; }
Possible output:
Original: {0, 1, 2, 7, 6, 6, 5, 5, 4, 3, 3} Erase all items divisible by 3: {1, 2, 7, 5, 5, 4} 5 items erased.
[edit] See also
removes elements satisfying specific criteria (function template) | |
(C++20)(C++20) |
removes elements satisfying specific criteria (algorithm function object) |