std::list<T,Allocator>::erase

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

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

vector<bool>

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

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Iterator invalidation

Member function table

Non-member function table

 

std::list

Member functions

list::list

list::~list

list::operator=

list::assign

list::assign_range (C++23)

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::insert_range (C++23)

list::emplace (C++11)

list::erase

list::push_front

list::emplace_front (C++11)

list::prepend_range (C++23)

list::pop_front

list::push_back

list::emplace_back (C++11)

list::append_range (C++23)

list::pop_back

list::resize

list::swap

Operations

list::merge

list::splice

list::removelist::remove_if

list::reverse

list::unique

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)
iterator erase( iterator pos );			(until C++11)
iterator erase( const_iterator pos );			(since C++11)
		(2)
iterator erase( iterator first, iterator last );				(until C++11)
iterator erase( const_iterator first, const_iterator last );				(since C++11)

Erases the specified elements from the container.

1) Removes the element at pos.

2) Removes the elements in the range [first, last).

References and iterators to the erased elements are invalidated. Other references and iterators are not affected.

The iterator pos must be valid and dereferenceable. Thus the end() iterator (which is valid, but is not dereferenceable) cannot be used as a value for pos.

The iterator first does not need to be dereferenceable if first == last: erasing an empty range is a no-op.

Parameters

pos	-	iterator to the element to remove
first, last	-	range of elements to remove

Return value

Iterator following the last removed element.

1) If pos refers to the last element, then the end() iterator is returned.

2) If last == end() prior to removal, then the updated end() iterator is returned.

If [first, last) is an empty range, then last is returned.

Exceptions

(none)

Complexity

1) Constant.

2) Linear in the distance between first and last.

Notes

When container elements need to be erased based on a predicate, rather than iterating the container and calling unary erase, the iterator range overload is generally used with std::remove()/std::remove_if() to minimise the number of moves of the remaining (non-removed) elements, this is the erase-remove idiom. std::erase_if() replaces the erase-remove idiom. (since C++20)

Example

Run this code

#include <list>
#include <iostream>
#include <iterator>
 
void print_container(const std::list<int>& c) 
{
    for (int i : c)
        std::cout << i << " ";
    std::cout << '\n';
}
 
int main( )
{
    std::list<int> c{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
    print_container(c);
 
    c.erase(c.begin());
    print_container(c);
 
    std::list<int>::iterator range_begin = c.begin();
    std::list<int>::iterator range_end = c.begin();
    std::advance(range_begin,2);
    std::advance(range_end,5);
 
    c.erase(range_begin, range_end);
    print_container(c);
 
    // Erase all even numbers
    for (std::list<int>::iterator it = c.begin(); it != c.end();)
    {
        if (*it % 2 == 0)
            it = c.erase(it);
        else
            ++it;
    }
    print_container(c);
}

Output:

0 1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 6 7 8 9
1 7 9

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 151	C++98	first was required to be dereferenceable, which made the behavior of clearing an empty list undefined	not required if first == last

See also

erase(std::list)erase_if(std::list) (C++20)	erases all elements satisfying specific criteria (function template)
clear	clears the contents (public member function)