std::erase_if (std::unordered_set)
From cppreference.com
< cpp | container | unordered set
Defined in header <unordered_set> | ||
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, autoconst& container){std::cout<< rem <<'{';for(char sep[]{0, ' ', 0};constauto& item : container)std::cout<< sep << item, *sep =',';std::cout<<"}\n";} int main(){std::unordered_set data{3, 3, 4, 5, 5, 6, 6, 7, 2, 1, 0}; println("Original:\n", data); auto divisible_by_3 =[](autoconst& x){return(x %3)==0;}; constauto 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, 5, 4, 3} Erase all items divisible by 3: {1, 2, 7, 5, 4} 3 items erased.[edit]See also
| removes elements satisfying specific criteria (function template) | |
(C++20)(C++20) | removes elements satisfying specific criteria (algorithm function object) |
