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std::erase_if(std::multiset)(3) | C++ Standard Libary | std::erase_if(std::multiset)(3) |
NAME¶
std::erase_if(std::multiset) - std::erase_if(std::multiset)
Synopsis¶
Defined in header <set>
template< class Key, class Compare, class Alloc, class Pred >
typename std::multiset<Key,Compare,Alloc>::size_type (since
C++20)
erase_if( std::multiset<Key,Compare,Alloc>& c, Pred pred );
Erases all elements that satisfy the predicate pred from the container.
Equivalent
to
auto old_size = c.size();
for (auto i = c.begin(), last = c.end(); i != last; ) {
if (pred(*i)) {
i = c.erase(i);
} else {
++i;
}
}
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 <set>
#include <iostream>
template<typename Os, typename Container>
inline Os& operator<<(Os& os, Container const& container)
{
os << "{ ";
for (const auto& item : container) {
os << item << ' ';
}
return os << "}";
}
int main()
{
std::multiset data { 3, 3, 4, 5, 5, 6, 6, 7, 2, 1, 0 };
std::cout << "Original:\n" << data << '\n';
auto divisible_by_3 = [](auto const& x) { return (x % 3) == 0; };
const auto count = std::erase_if(data, divisible_by_3);
std::cout << "Erase all items divisible by 3:\n" <<
data << '\n'
<< 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.
See also¶
remove removes elements satisfying specific criteria
remove_if (function template)
2022.07.31 | http://cppreference.com |