std::ranges::uninitialized_move, std::ranges::uninitialized_move_result

Header: <memory>

Let (\scriptsize N)N be ranges::min(ranges::distance(ifirst, ilast), ranges::distance(ofirst, olast)).

# Declarations

Call signature
template< std::input_iterator I, std::sentinel_for<I> S1,
no-throw-forward-iterator O, no-throw-sentinel-for<O> S2 >
requires std::constructible_from<std::iter_value_t<O>,
std::iter_rvalue_reference_t<I>>
uninitialized_move_result<I, O>
uninitialized_move( I ifirst, S1 ilast, O ofirst, S2 olast );

(since C++20) (constexpr since C++26)

template< ranges::input_range IR, no-throw-forward-range OR >
requires std::constructible_from
<ranges::range_value_t<OR>,
ranges::range_rvalue_reference_t<IR>>
uninitialized_move_result<ranges::borrowed_iterator_t<IR>,
ranges::borrowed_iterator_t<OR>>
uninitialized_move( IR&& in_range, OR&& out_range );

(since C++20) (constexpr since C++26)

Helper types
template< class I, class O >
using uninitialized_move_result = ranges::in_out_result<I, O>;

(since C++20)

# Parameters

# Return value

As described above.

# Notes

An implementation may improve the efficiency of the ranges::uninitialized_move, e.g. by using ranges::copy_n, if the value type of the output range is TrivialType.

# Example

#include <cstdlib>
#include <iomanip>
#include <iostream>
#include <memory>
#include <string>
 
void print(auto rem, auto first, auto last)
{
    for (std::cout << rem; first != last; ++first)
        std::cout << std::quoted(*first) << ' ';
    std::cout << '\n';
}
 
int main()
{
    std::string in[]{"Home", "World"};
    print("initially, in: ", std::begin(in), std::end(in));
 
    if (constexpr auto sz = std::size(in);
        void* out = std::aligned_alloc(alignof(std::string), sizeof(std::string) * sz))
    {
        try
        {
            auto first{static_cast<std::string*>(out)};
            auto last{first + sz};
            std::ranges::uninitialized_move(std::begin(in), std::end(in), first, last);
 
            print("after move, in: ", std::begin(in), std::end(in));
            print("after move, out: ", first, last);
 
            std::ranges::destroy(first, last);
        }
        catch (...)
        {
            std::cout << "Exception!\n";
        }
        std::free(out);
    }
}

# Defect reports

DRApplied toBehavior as publishedCorrect behavior
LWG 3870C++20this algorithm might create objects on a const storagekept disallowed

# See also