std::erase_if (std::flat_multimap)
From cppreference.com
< cpp | container | flat multimap
| Defined in header <flat_map>
|
||
| template< class Key, class T, class Compare, class KeyContainer, class MappedContainer, class Pred > |
(since C++23) | |
Erases all elements that satisfy the predicate pred from c.
The predicate pred is satisfied if the expression bool(pred(std::pair<const Key&, const T&>(e))) is true, where e is some element in c.
Key and T must be MoveAssignable. Otherwise, the behavior is undefined.
Parameters
| c | - | container adaptor from which to erase |
| pred | - | predicate that returns true if the element should be erased |
Return value
The number of erased elements.
Complexity
Exactly c.size() applications of the predicate pred.
Exceptions
If erase_if throws, c remains in valid but unspecified (maybe empty) state.
Notes
The algorithm is stable, that is, the order of elements that are not deleted remains unchanged.
Example
Run this code
#include <iostream> #include <flat_map> void println(auto rem, auto const& container) { std::cout << rem << '{'; for (char sep[]{0, ' ', 0}; const auto& [key, value] : container) std::cout << sep << '{' << key << ", " << value << '}', *sep = ','; std::cout << "}\n"; } int main() { std::flat_multimap<int, char> data { {1, 'a'}, {2, 'b'}, {3, 'c'}, {4, 'd'}, {5, 'e'}, {4, 'f'}, {5, 'g'}, {5, 'g'}, }; println("Original:\n", data); const auto count = std::erase_if(data, [](const auto& item) { auto const& [key, value] = item; return (key & 1) == 1; }); println("Erase items with odd keys:\n", data); std::cout << count << " items removed.\n"; }
Output:
Original:
{{1, a}, {2, b}, {3, c}, {4, d}, {4, f}, {5, e}, {5, g}, {5, g}}
Erase items with odd keys:
{{2, b}, {4, d}, {4, f}}
5 items removed.See also
| removes elements satisfying specific criteria (function template) | |
| (C++20)(C++20) |
removes elements satisfying specific criteria (niebloid) |