std::forward_list<T,Allocator>::remove, remove_if
From cppreference.com
< cpp | container | forward list
| (1) | ||
void remove( const T& value ); |
(since C++11) (until C++20) |
|
| size_type remove( const T& value ); |
(since C++20) | |
| (2) | ||
template< class UnaryPredicate > void remove_if( UnaryPredicate p ); |
(since C++11) (until C++20) |
|
| template< class UnaryPredicate > size_type remove_if( UnaryPredicate p ); |
(since C++20) | |
Removes all elements satisfying specific criteria. Invalidates only the iterators and references to the removed elements.
1) Removes all elements that are equal to value (using operator==).
2) Removes all elements for which predicate p returns true.
Parameters
| value | - | value of the elements to remove |
| p | - | unary predicate which returns true if the element should be removed. The expression p(v) must be convertible to bool for every argument |
| Type requirements | ||
-UnaryPredicate must meet the requirements of Predicate.
| ||
Return value
|
(none) |
(until C++20) |
|
The number of elements removed. |
(since C++20) |
Complexity
Given N as std::distance(begin(), end()):
1) Exactly N comparisons using operator==.
2) Exactly N applications of the predicate p.
Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_list_remove_return_type |
201806L |
(C++20) | Change the return type |
Example
Run this code
#include <forward_list> #include <iostream> int main() { std::forward_list<int> l = {1, 100, 2, 3, 10, 1, 11, -1, 12}; auto count1 = l.remove(1); std::cout << count1 << " elements equal to 1 were removed\n"; auto count2 = l.remove_if([](int n){ return n > 10; }); std::cout << count2 << " elements greater than 10 were removed\n"; std::cout << "Finally, the list contains: "; for (int n : l) std::cout << n << ' '; std::cout << '\n'; }
Output:
2 elements equal to 1 were removed 3 elements greater than 10 were removed Finally, the list contains: 2 3 10 -1
See also
| removes elements satisfying specific criteria (function template) |