std::erase, std::erase_if (std::list)

 

C++

Language

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Named requirements

Language support library

Concepts library (C++20)

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Regular expressions library (C++11)

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Technical Specifications

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

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multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

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span (C++20)

 

std::list

Member functions

list::list

list::~list

list::operator=

list::assign

list::get_allocator

Element access

list::front

list::back

Iterators

list::beginlist::cbegin (C++11)

list::endlist::cend (C++11)

list::rbeginlist::crbegin (C++11)

list::rendlist::crend (C++11)

Capacity

list::empty

list::size

list::max_size

Modifiers

list::clear

list::insert

list::emplace (C++11)

list::erase

list::push_front

list::emplace_front (C++11)

list::pop_front

list::push_back

list::emplace_back (C++11)

list::pop_back

list::resize

list::swap

Operations

list::merge

list::splice

list::removelist::remove_if

list::reverse

list::unique

list::sort

Deduction guides(C++17)

 

Defined in header <list>
template< class T, class Alloc, class U > typename std::list<T,Alloc>::size_type     erase(std::list<T,Alloc>& c, const U& value);	(1)	(since C++20)
template< class T, class Alloc, class Pred > typename std::list<T,Alloc>::size_type     erase_if(std::list<T,Alloc>& c, Pred pred);	(2)	(since C++20)

1) Erases all elements that compare equal to value from the container. Equivalent to return c.remove_if([&](auto& elem) { return elem == value; });

2) Erases all elements that satisfy the predicate pred from the container. Equivalent to return c.remove_if(pred);

Parameters

c	-	container from which to erase
value	-	value to be removed
pred	-	unary predicate which returns ​true if the element should be erased. The expression pred(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). ​

Complexity

Linear.

Example

Run this code

#include <iostream>
#include <numeric>
#include <list>
 
void print_container(const std::list<char>& c)
{
    for (auto x : c) {
        std::cout << x << ' ';
    }
    std::cout << '\n';
}
 
int main()
{
    std::list<char> cnt(10);
    std::iota(cnt.begin(), cnt.end(), '0');
 
    std::cout << "Init:\n";
    print_container(cnt);
 
    std::erase(cnt, '5');
    std::cout << "Erase \'5\':\n";
    print_container(cnt);
 
    std::erase_if(cnt, [](char x) { return (x - '0') % 2 == 0; });
    std::cout << "Erase all even numbers:\n";
    print_container(cnt);
}

Output:

Init:
0 1 2 3 4 5 6 7 8 9 
Erase '5':
0 1 2 3 4 6 7 8 9 
Erase all even numbers:
1 3 7 9

Notes

Unlike std::list::remove, erase accepts heterogenous types and does not force a conversion to the container's value type before invoking the == operator.

See also

removeremove_if	removes elements satisfying specific criteria (function template)
removeremove_if	removes elements satisfying specific criteria (public member function)