std:: erase_if (std::unordered_multiset)
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Defined in header
<unordered_set>
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||
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template
<
class
Key,
class
Hash,
class
KeyEqual,
class
Alloc,
class
Pred
>
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(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
#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.
See also
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removes elements satisfying specific criteria
(function template) |
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(C++20)
(C++20)
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removes elements satisfying specific criteria
(algorithm function object) |