std::swap(std::forward_list)

Defined in header `<forward_list>`
template< class T, class Alloc > void swap( std::forward_list<T,Alloc>& lhs, std::forward_list<T,Alloc>& rhs );		(since C++11) (until C++17)
template< class T, class Alloc > void swap( std::forward_list<T,Alloc>& lhs, std::forward_list<T,Alloc>& rhs ) noexcept(/* see below */);		(since C++17)

Specializes the std::swap algorithm for std::forward_list. Swaps the contents of lhs and rhs. Calls lhs.swap(rhs).

Parameters

lhs, rhs

-

containers whose contents to swap

Return value

(none)

Complexity

Constant.

Exceptions

noexcept specification:

noexcept(noexcept(lhs.swap(rhs)))

(since C++17)

Notes

Although the overloads of std::swap for container adaptors are introduced in C++11, container adaptors can already be swapped by std::swap in C++98. Such calls to std::swap usually have linear time complexity, but better complexity may be provided.

Example

Run this code

#include <algorithm>
#include <iostream>
#include <forward_list>
 
int main()
{
    std::forward_list<int> alice{1, 2, 3};
    std::forward_list<int> bob{7, 8, 9, 10};
 
    auto print = [](const int& n) { std::cout << ' ' << n; };
 
    // Print state before swap
    std::cout << "alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\n" "bob  :";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
 
    std::cout << "-- SWAP\n";
    std::swap(alice, bob);
 
    // Print state after swap
    std::cout << "alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\n" "bob  :";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
}

Output:

alice: 1 2 3
bob  : 7 8 9 10
-- SWAP
alice: 7 8 9 10
bob  : 1 2 3

Compiler support
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Language
Standard library headers
Named requirements
Feature test macros (C++20)
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Technical specifications
Symbols index
External libraries

Sequence
array (C++11)
vector
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
Views
span (C++20)

Member functions
forward_list::forward_list
forward_list::~forward_list
forward_list::operator=
forward_list::assign
forward_list::get_allocator
Element access
forward_list::front
Iterators
forward_list::before_beginforward_list::cbefore_begin
forward_list::beginforward_list::cbegin
forward_list::endforward_list::cend
Capacity
forward_list::empty
forward_list::max_size
Modifiers
forward_list::clear
forward_list::insert_after
forward_list::emplace_after
forward_list::erase_after
forward_list::push_front
forward_list::emplace_front
forward_list::pop_front
forward_list::resize
forward_list::swap
Operations
forward_list::merge
forward_list::splice_after
forward_list::removeforward_list::remove_if
forward_list::reverse
forward_list::unique
forward_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)