std::forward_list<T,Allocator>::remove, remove_if

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

Views

span (C++20)

 

std::forward_list

Member functions

forward_list::forward_list

forward_list::~forward_list

forward_list::operator=

forward_list::assign

forward_list::get_allocator

Element access

forward_list::front

Iterators

forward_list::before_beginforward_list::cbefore_begin

forward_list::beginforward_list::cbegin

forward_list::endforward_list::cend

Capacity

forward_list::empty

forward_list::max_size

Modifiers

forward_list::clear

forward_list::insert_after

forward_list::emplace_after

forward_list::erase_after

forward_list::push_front

forward_list::emplace_front

forward_list::pop_front

forward_list::resize

forward_list::swap

Operations

forward_list::merge

forward_list::splice_after

forward_list::removeforward_list::remove_if

forward_list::reverse

forward_list::unique

forward_list::sort

Non-member functions

std::swap

eraseerase_if (C++20)(C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides(C++17)

 

	(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.

1) Removes all elements that are equal to value.

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 v of type (possibly const) T, regardless of value category, and must not modify v. Thus, a parameter type of T&is not allowed, nor is T unless for T a move is equivalent to a copy (since C++11). ​

Return value

(none)	(until C++20)
The number of elements removed.	(since C++20)

Complexity

Linear in the size of the container

Notes

Feature-test macro:

__cpp_lib_list_remove_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

removeremove_if

removes elements satisfying specific criteria (function template)