std:: erase_if (std::multiset)

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C++
Containers library
std::multiset
Member functions
Non-member functions
erase_if (std::multiset)
(C++20)
(C++20)

(until C++20) (until C++20) (until C++20) (until C++20) (until C++20)
Deduction guides (C++17)
Defined in header <set>
template < class Key, class Compare, class Alloc,

class Pred >
std:: multiset < Key, Compare, Alloc > :: size_type
erase_if ( std:: multiset < 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::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";
}

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

removes elements satisfying specific criteria
(function template)
(C++20) (C++20)
removes elements satisfying specific criteria
(algorithm function object)
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