std::forward_list<T,Allocator>::swap

Since C++17

Exchanges the contents of the container with those of other. Does not invoke any move, copy, or swap operations on individual elements.

# Declarations

void swap( forward_list& other );

(since C++11) (until C++17)

void swap( forward_list& other ) noexcept(/* see below */);

(since C++17)

# Parameters

# Example

#include <iostream>
#include <forward_list>
 
template<class Os, class Co>
Os& operator<<(Os& os, const Co& co)
{
    os << '{';
    for (auto const& i : co)
        os << ' ' << i;
    return os << " } ";
}
 
int main()
{
    std::forward_list<int> a1{1, 2, 3}, a2{4, 5};
 
    auto it1 = std::next(a1.begin());
    auto it2 = std::next(a2.begin());
 
    int& ref1 = a1.front();
    int& ref2 = a2.front();
 
    std::cout << a1 << a2 << *it1 << ' ' << *it2 << ' ' << ref1 << ' ' << ref2 << '\n';
    a1.swap(a2);
    std::cout << a1 << a2 << *it1 << ' ' << *it2 << ' ' << ref1 << ' ' << ref2 << '\n';
 
    // Note that after swap the iterators and references stay associated with their
    // original elements, e.g. it1 that pointed to an element in 'a1' with value 2
    // still points to the same element, though this element was moved into 'a2'.
}

# See also