std::swap_ranges

Since C++17

Header: <algorithm>

Exchanges elements between range [first1,last1) and another range of std::distance(first1, last1) elements starting at first2.

# Declarations

template< class ForwardIt1, class ForwardIt2 >
ForwardIt2 swap_ranges( ForwardIt1 first1, ForwardIt1 last1,
ForwardIt2 first2 );

(constexpr since C++20)

template< class ExecutionPolicy,
class ForwardIt1, class ForwardIt2 >
ForwardIt2 swap_ranges( ExecutionPolicy&& policy,
ForwardIt1 first1, ForwardIt1 last1,
ForwardIt2 first2 );

(since C++17)

# Parameters

first1, last1: the first range of elements to swap
first2: beginning of the second range of elements to swap
policy: the execution policy to use

# Return value

Iterator to the element past the last element exchanged in the range beginning with first2.

# Notes

Implementations (e.g. MSVC STL) may enable vectorization when the iterator type satisfies LegacyContiguousIterator and swapping its value type calls neither non-trivial special member function nor ADL-found swap.

# Example

#include <algorithm>
#include <iostream>
#include <list>
#include <vector>
 
auto print = [](auto comment, auto const& seq)
{
    std::cout << comment;
    for (const auto& e : seq)
        std::cout << e << ' ';
    std::cout << '\n';
};
 
int main()
{
    std::vector<char> v{'a', 'b', 'c', 'd', 'e'};
    std::list<char> l{'1', '2', '3', '4', '5'};
 
    print("Before swap_ranges:\n" "v: ", v);
    print("l: ", l);
 
    std::swap_ranges(v.begin(), v.begin() + 3, l.begin());
 
    print("After swap_ranges:\n" "v: ", v);
    print("l: ", l);
}