std::forward_list
| Defined in header <forward_list>
|
||
| template< class T, |
(1) | (since C++11) |
| namespace pmr { template< class T > |
(2) | (since C++17) |
std::forward_list is a container that supports fast insertion and removal of elements from anywhere in the container. Fast random access is not supported. It is implemented as a singly-linked list. Compared to std::list this container provides more space efficient storage when bidirectional iteration is not needed.
Adding, removing and moving the elements within the list, or across several lists, does not invalidate the iterators currently referring to other elements in the list. However, an iterator or reference referring to an element is invalidated when the corresponding element is removed (via erase_after) from the list.
std::forward_list meets the requirements of Container (except for the size member function and that operator=='s complexity is always linear), AllocatorAwareContainer and SequenceContainer.
All member functions of std::forward_list are constexpr: it is possible to create and use std::forward_list objects in the evaluation of a constant expression.However, |
(since C++26) |
Contents |
[edit] Template parameters
| T | - | The type of the elements.
| ||||||||||||
| Allocator | - | 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. 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.
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[edit] 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& |
pointer
|
std::allocator_traits<Allocator>::pointer |
const_pointer
|
std::allocator_traits<Allocator>::const_pointer |
iterator
|
LegacyForwardIterator and ConstexprIterator(since C++26) to value_type
|
const_iterator
|
LegacyForwardIterator and ConstexprIterator(since C++26) to const value_type |
[edit] Member functions
constructs the forward_list (public member function) | |
destructs the forward_list (public member function) | |
| assigns values to the container (public member function) | |
| assigns values to the container (public member function) | |
| (C++23) |
assigns a range of values to the container (public member function) |
| returns the associated allocator (public member function) | |
Element access | |
| access the first element (public member function) | |
Iterators | |
| returns an iterator to the element before beginning (public member function) | |
| returns an iterator to the beginning (public member function) | |
| returns an iterator to the end (public member function) | |
Capacity | |
| checks whether the container is empty (public member function) | |
| returns the maximum possible number of elements (public member function) | |
Modifiers | |
| clears the contents (public member function) | |
| inserts elements after an element (public member function) | |
| constructs elements in-place after an element (public member function) | |
| (C++23) |
inserts a range of elements after an element (public member function) |
| erases an element after an element (public member function) | |
| inserts an element to the beginning (public member function) | |
| constructs an element in-place at the beginning (public member function) | |
| (C++23) |
adds a range of elements to the beginning (public member function) |
| removes the first element (public member function) | |
| changes the number of elements stored (public member function) | |
| swaps the contents (public member function) | |
Operations | |
| merges two sorted lists (public member function) | |
transfers elements from another forward_list (public member function) | |
| removes elements satisfying specific criteria (public member function) | |
| reverses the order of the elements (public member function) | |
| removes consecutive duplicate elements (public member function) | |
| sorts the elements (public member function) | |
[edit] Non-member functions
| (C++11)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++11)(removed in C++20)(C++20) |
lexicographically compares the values of two forward_lists (function template) |
| (C++11) |
specializes the std::swap algorithm (function template) |
| erases all elements satisfying specific criteria (function template) |
Deduction guides |
(since C++17) |
[edit] Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_containers_ranges |
202202L |
(C++23) | Ranges construction and insertion for containers |
__cpp_lib_constexpr_forward_list |
202502L |
(C++26) | constexpr std::forward_list
|
[edit] Example
| This section is incomplete Reason: no example |
[edit] See also
| doubly-linked list (class template) |
