NAME¶

std::list - std::list

Synopsis¶

Defined in header <list>
template<

class T, (1)
class Allocator = std::allocator<T>

> class list;
namespace pmr {

template< class T > (2) (since C++17)
using list = std::list<T, std::pmr::polymorphic_allocator<T>>;

}

std::list is a container that supports constant time insertion and removal of
elements from anywhere in the container. Fast random access is not supported. It is
usually implemented as a doubly-linked list. Compared to std::forward_list this
container provides bidirectional iteration capability while being less space
efficient.

Adding, removing and moving the elements within the list or across several lists
does not invalidate the iterators or references. An iterator is invalidated only
when the corresponding element is deleted.

std::list meets the requirements of Container, AllocatorAwareContainer,
SequenceContainer and ReversibleContainer.

Template parameters¶

The type of the elements.

T must meet the requirements of CopyConstructible. T must meet the (until
requirements of CopyAssignable if list::operator= or list::assign C++11)
is instantiated with T.
The requirements that are imposed on the elements depend on the (since
actual operations performed on the container. Generally, it is C++11)
required that element type is a complete type and meets the (until
requirements of Erasable, but many member functions impose C++17)
stricter requirements.
The requirements that are imposed on the elements depend on the
actual operations performed on the container. Generally, it is
T - required that element type meets the requirements of Erasable, but
many member functions impose stricter requirements. This container
(but not its members) can be instantiated with an incomplete
element type if the allocator satisfies the allocator completeness (since
requirements. C++17)

Feature-test macro Value Std Feature
Minimal
__cpp_lib_incomplete_container_elements 201505L (C++17) incomplete
type
support

An allocator that is used to acquire/release memory and to
construct/destroy the elements in that memory. The type must meet the
requirements of Allocator.
Allocator - The behavior is undefined
(until C++20)
The program is ill-formed
(since C++20) if Allocator::value_type is not the same as T.

Member types¶

Member type Definition
value_type T
allocator_type Allocator
size_type Unsigned integer type (usually std::size_t)
difference_type Signed integer type (usually std::ptrdiff_t)
reference value_type&
const_reference const value_type&
Allocator::pointer (until C++11)
pointer std::allocator_traits<Allocator>::pointer (since C++11)

Allocator::const_pointer (until C++11)
const_pointer std::allocator_traits<Allocator>::const_pointer (since C++11)

iterator LegacyBidirectionalIterator to value_type
const_iterator LegacyBidirectionalIterator to const value_type
reverse_iterator std::reverse_iterator<iterator>
const_reverse_iterator std::reverse_iterator<const_iterator>

Member functions¶

constructor constructs the list
(public member function)
destructor destructs the list
(public member function)
operator= assigns values to the container
(public member function)
assign assigns values to the container
(public member function)
assign_range assigns a range of values to the container
(C++23) (public member function)
get_allocator returns the associated allocator
(public member function)

Element access¶

front access the first element
(public member function)
back access the last element
(public member function)

Iterators¶

begin returns an iterator to the beginning
cbegin (public member function)
(C++11)
end returns an iterator to the end
cend (public member function)
(C++11)
rbegin returns a reverse iterator to the beginning
crbegin (public member function)
(C++11)
rend returns a reverse iterator to the end
crend (public member function)
(C++11)

Capacity¶

empty checks whether the container is empty
(public member function)
size returns the number of elements
(public member function)
max_size returns the maximum possible number of elements
(public member function)

Modifiers¶

clear clears the contents
(public member function)
insert inserts elements
(public member function)
insert_range inserts a range of elements
(C++23) (public member function)
emplace constructs element in-place
(C++11) (public member function)
erase erases elements
(public member function)
push_back adds an element to the end
(public member function)
emplace_back constructs an element in-place at the end
(C++11) (public member function)
append_range adds a range of elements to the end
(C++23) (public member function)
pop_back removes the last element
(public member function)
push_front inserts an element to the beginning
(public member function)
emplace_front constructs an element in-place at the beginning
(C++11) (public member function)
prepend_range adds a range of elements to the beginning
(C++23) (public member function)
pop_front removes the first element
(public member function)
resize changes the number of elements stored
(public member function)
swap swaps the contents
(public member function)

Operations¶

merge merges two sorted lists
(public member function)
splice moves elements from another list
(public member function)
remove removes elements satisfying specific criteria
remove_if (public member function)
reverse reverses the order of the elements
(public member function)
unique removes consecutive duplicate elements
(public member function)
sort sorts the elements
(public member function)

Non-member functions¶

operator==
operator!=
operator<
operator<=
operator>
operator>= lexicographically compares the values of two lists
operator<=> (function template)
(removed in C++20)
(removed in C++20)
(removed in C++20)
(removed in C++20)
(removed in C++20)
(C++20)
std::swap(std::list) specializes the std::swap algorithm
(function template)
erase(std::list) erases all elements satisfying specific criteria
erase_if(std::list) (function template)
(C++20)

Deduction guides (since C++17)

Notes¶

Feature-test macro Value Std Feature
__cpp_lib_containers_ranges 202202L (C++23) Ranges construction and insertion for
containers

Example¶

// Run this code

#include <algorithm>
#include <iostream>
#include <list>

int main()
{
// Create a list containing integers
std::list<int> l = {7, 5, 16, 8};

// Add an integer to the front of the list
l.push_front(25);
// Add an integer to the back of the list
l.push_back(13);

// Insert an integer before 16 by searching
auto it = std::find(l.begin(), l.end(), 16);
if (it != l.end())
l.insert(it, 42);

// Print out the list
std::cout << "l = { ";
for (int n : l)
std::cout << n << ", ";
std::cout << "};\n";
}

Output:¶

l = { 25, 7, 5, 42, 16, 8, 13, };

Defect reports

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

DR Applied to Behavior as published Correct behavior
T was not required to be
LWG 230 C++98 CopyConstructible T is also required to
(an element of type T might not be be CopyConstructible
able to be constructed)
LWG 276 C++98 T was always required to be only required if operator= or
CopyAssignable assign is instantiated with T