Standard library header <forward_list> (C++11)

 

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Language support <cfloat> <climits> <compare> (C++20) <contracts> (C++26) <coroutine> (C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint> (C++11) <cstdlib> <exception> <initializer_list> (C++11)   <limits> <new> <source_location> (C++20) <stdfloat> (C++23) <typeinfo> <version> (C++20) Concepts <concepts> (C++20) Diagnostics <cassert> <cerrno> <debugging> (C++26) <stacktrace> (C++23) <stdexcept> <system_error> (C++11) Memory management <memory> <memory_resource> (C++17) <scoped_allocator> (C++11) Metaprogramming <meta> (C++26) <ratio> (C++11) <type_traits> (C++11)

General utilities <any> (C++17) <bitset> <bit> (C++20) <charconv> (C++17) <expected> (C++23) <format> (C++20) <functional> <optional> (C++17) <stdbit.h> (C++26) <tuple> (C++11) <typeindex> (C++11) <utility> <variant> (C++17) Containers <array> (C++11) <deque> <flat_map> (C++23) <flat_set> (C++23) <forward_list> (C++11) <hive> (C++26) <inplace_vector> (C++26)   <list> <map> <mdspan> (C++23) <queue> <set> <span> (C++20) <stack> <unordered_map> (C++11) <unordered_set> (C++11) <vector> Iterators <iterator> Ranges <generator> (C++23) <ranges> (C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar> (C++11) <cwchar> <cwctype> <string_view> (C++17) <string> Text processing <clocale> <codecvt> (C++11/17/26*) <locale> <regex> (C++11) <text_encoding> (C++26)   Numerics <cfenv> (C++11) <cmath> <complex> <linalg> (C++26) <numbers> (C++20) <random> (C++11) <simd> (C++26) <stdckdint.h> (C++26) <valarray> Time <chrono> (C++11) <ctime> C compatibility <ccomplex> (C++11/17/20*) <ciso646> (until C++20) <cstdalign> (C++11/17/20*) <cstdbool> (C++11/17/20*) <ctgmath> (C++11/17/20*)

Input/output <cinttypes> (C++11) <cstdio> <filesystem> (C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print> (C++23) <spanstream> (C++23) <sstream> <streambuf> <strstream> (C++98/26*) <syncstream> (C++20) Concurrency support <atomic> (C++11) <barrier> (C++20) <condition_variable> (C++11) <future> (C++11) <hazard_pointer> (C++26) <latch> (C++20) <mutex> (C++11) <rcu> (C++26) <semaphore> (C++20) <shared_mutex> (C++14) <stdatomic.h> (C++23) <stop_token> (C++20) <thread> (C++11) Execution support <execution> (C++17)

 

See More

This header is part of the containers library.

Includes
<compare> (C++20)	Three-way comparison operator support
<initializer_list> (C++11)	std::initializer_list class template
Classes
forward_list (C++11)	singly-linked list (class template)
Functions
operator==operator!=operator<operator<=operator>operator>=operator<=> (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)
std::swap(std::forward_list) (C++11)	specializes the std::swap algorithm (function template)
erase(std::forward_list)erase_if(std::forward_list) (C++20)	erases all elements satisfying specific criteria (function template)
Range access
begincbegin (C++11)(C++14)	returns an iterator to the beginning of a container or array (function template)
endcend (C++11)(C++14)	returns an iterator to the end of a container or array (function template)
rbegincrbegin (C++14)	returns a reverse iterator to the beginning of a container or array (function template)
rendcrend (C++14)	returns a reverse end iterator for a container or array (function template)
sizessize (C++17)(C++20)	returns the size of a container or array (function template)
empty (C++17)	checks whether the container is empty (function template)
data (C++17)	obtains the pointer to the underlying array (function template)

Synopsis

#include <compare>
#include <initializer_list>

namespace std {
  // class template forward_list
  template<class T, class Allocator = allocator<T>> class forward_list;

  template<class T, class Allocator>
  constexpr bool operator==(const forward_list<T, Allocator>& x,
                            const forward_list<T, Allocator>& y);
  template<class T, class Allocator>
  constexpr /*synth-three-way-result*/<T> operator<=>(
    const forward_list<T, Allocator>& x, const forward_list<T, Allocator>& y);

  template<class T, class Allocator>
  constexpr void swap(forward_list<T, Allocator>& x,
                      forward_list<T, Allocator>& y) noexcept(noexcept(x.swap(y)));

  // erasure
  template<class T, class Allocator, class U = T>
  constexpr typename forward_list<T, Allocator>::size_type erase(
    forward_list<T, Allocator>& c, const U& value);
  template<class T, class Allocator, class Predicate>
  constexpr typename forward_list<T, Allocator>::size_type erase_if(
    forward_list<T, Allocator>& c, Predicate pred);

  namespace pmr {
    template<class T> using forward_list = std::forward_list<T, polymorphic_allocator<T>>;
  }
}

Class template std::forward_list

namespace std {
  template<class T, class Allocator = allocator<T>> class forward_list
  {
  public:
    // types
    using value_type = T;
    using allocator_type = Allocator;
    using pointer = allocator_traits<Allocator>::pointer;
    using const_pointer = allocator_traits<Allocator>::const_pointer;
    using reference = value_type&;
    using const_reference = const value_type&;
    using size_type = /* implementation-defined */;
    using difference_type = /* implementation-defined */;
    using iterator = /* implementation-defined */;
    using const_iterator = /* implementation-defined */;

    // construct/copy/destroy
    constexpr forward_list()
      : forward_list(Allocator())
    {
    }
    constexpr explicit forward_list(const Allocator&);
    constexpr explicit forward_list(size_type n, const Allocator& = Allocator());
    constexpr forward_list(size_type n, const T& value, const Allocator& = Allocator());
    template<class InputIter>
    constexpr forward_list(InputIter first,
                           InputIter last,
                           const Allocator& = Allocator());
    template<container-compatible-range<T> R>
    constexpr forward_list(from_range_t, R&& rg, const Allocator& = Allocator());
    constexpr forward_list(const forward_list& x);
    constexpr forward_list(forward_list&& x);
    constexpr forward_list(const forward_list& x, const type_identity_t<Allocator>&);
    constexpr forward_list(forward_list&& x, const type_identity_t<Allocator>&);
    constexpr forward_list(initializer_list<T>, const Allocator& = Allocator());
    constexpr ~forward_list();
    constexpr forward_list& operator=(const forward_list& x);
    constexpr forward_list& operator=(forward_list&& x) noexcept(
      allocator_traits<Allocator>::is_always_equal::value);
    constexpr forward_list& operator=(initializer_list<T>);
    template<class InputIter> constexpr void assign(InputIter first, InputIter last);
    template<container-compatible-range<T> R> constexpr void assign_range(R&& rg);
    constexpr void assign(size_type n, const T& t);
    constexpr void assign(initializer_list<T>);
    constexpr allocator_type get_allocator() const noexcept;

    // iterators
    constexpr iterator before_begin() noexcept;
    constexpr const_iterator before_begin() const noexcept;
    constexpr iterator begin() noexcept;
    constexpr const_iterator begin() const noexcept;
    constexpr iterator end() noexcept;
    constexpr const_iterator end() const noexcept;

    constexpr const_iterator cbegin() const noexcept;
    constexpr const_iterator cbefore_begin() const noexcept;
    constexpr const_iterator cend() const noexcept;

    // capacity
    constexpr bool empty() const noexcept;
    constexpr size_type max_size() const noexcept;

    // element access
    constexpr reference front();
    constexpr const_reference front() const;

    // modifiers
    template<class... Args> constexpr reference emplace_front(Args&&... args);
    constexpr void push_front(const T& x);
    constexpr void push_front(T&& x);
    template<container-compatible-range<T> R> constexpr void prepend_range(R&& rg);
    constexpr void pop_front();

    template<class... Args>
    constexpr iterator emplace_after(const_iterator position, Args&&... args);
    constexpr iterator insert_after(const_iterator position, const T& x);
    constexpr iterator insert_after(const_iterator position, T&& x);

    constexpr iterator insert_after(const_iterator position, size_type n, const T& x);
    template<class InputIter>
    constexpr iterator insert_after(const_iterator position,
                                    InputIter first,
                                    InputIter last);
    constexpr iterator insert_after(const_iterator position, initializer_list<T> il);
    template<container-compatible-range<T> R>
    constexpr iterator insert_range_after(const_iterator position, R&& rg);

    constexpr iterator erase_after(const_iterator position);
    constexpr iterator erase_after(const_iterator position, const_iterator last);
    constexpr void swap(forward_list&) noexcept(
      allocator_traits<Allocator>::is_always_equal::value);

    constexpr void resize(size_type sz);
    constexpr void resize(size_type sz, const value_type& c);
    constexpr void clear() noexcept;

    // forward_list operations
    constexpr void splice_after(const_iterator position, forward_list& x);
    constexpr void splice_after(const_iterator position, forward_list&& x);
    constexpr void splice_after(const_iterator position,
                                forward_list& x,
                                const_iterator i);
    constexpr void splice_after(const_iterator position,
                                forward_list&& x,
                                const_iterator i);
    constexpr void splice_after(const_iterator position,
                                forward_list& x,
                                const_iterator first,
                                const_iterator last);
    constexpr void splice_after(const_iterator position,
                                forward_list&& x,
                                const_iterator first,
                                const_iterator last);

    constexpr size_type remove(const T& value);
    template<class Predicate> constexpr size_type remove_if(Predicate pred);

    constexpr size_type unique();
    template<class BinaryPredicate>
    constexpr size_type unique(BinaryPredicate binary_pred);

    constexpr void merge(forward_list& x);
    constexpr void merge(forward_list&& x);
    template<class Compare> constexpr void merge(forward_list& x, Compare comp);
    template<class Compare> constexpr void merge(forward_list&& x, Compare comp);

    constexpr void sort();
    template<class Compare> constexpr void sort(Compare comp);

    constexpr void reverse() noexcept;
  };

  template<class InputIter, class Allocator = allocator</*iter-value-type*/<InputIter>>>
  forward_list(InputIter, InputIter, Allocator = Allocator())
    -> forward_list</*iter-value-type*/<InputIter>, Allocator>;

  template<ranges::input_range R, class Allocator = allocator<ranges::range_value_t<R>>>
  forward_list(from_range_t, R&&, Allocator = Allocator())
    -> forward_list<ranges::range_value_t<R>, Allocator>;
}