std::ranges::in_out_result(3)

NAME
std::ranges::in_out_result - std::ranges::in_out_result

Synopsis
   Defined in header <algorithm>
   template< class I, class O > (since C++20)
   struct in_out_result;
   ranges::in_out_result is a class template that provides a way to store two iterators
   as a single unit.
   This class template has no base classes or declared members other than those shown
   below. Thus it is suitable for use with structured bindings.
   All special member functions of this class template are implicitly declared, which
   makes specializations be aggregate classes, and propagate triviality,
   potentially-throwing-ness, and constexpr-ness of corresponding operations on data
   members.

Template parameters
   I, O - the types of the objects that the ranges::in_out_result stores.
   Data members
   Member name Definition
   in a value (that is supposed to be an iterator) of type I.
               (public member object)
   out a value (that is supposed to be an iterator) of type O.
               (public member object)
   All these members are declared with [[no_unique_address]] attribute.

Member functions
std::ranges::in_out_result::operator in_out_result<I2, O2>
   template<class I2, class O2>
   requires std::convertible_to<const I&, I2> && std::convertible_to<const O&, O2> (1)
   constexpr operator in_out_result<I2, O2>() const &;
   template<class I2, class O2>
   requires std::convertible_to<I, I2> && std::convertible_to<O, O2> (2)
   constexpr operator in_out_result<I2, O2>() &&;
   Converts *this to the result by constructing every data member of the result from
   the corresponding member of *this.
   1) Equivalent to return {in, out};.
   2) Equivalent to return {std::move(in), std::move(out)};.

Standard library
   The following standard library functions use ranges::in_out_result as the return
   type:
         Algorithm functions
   ranges::copy
   ranges::copy_if copies a range of elements to a new location
   (C++20) (niebloid)
   (C++20)
   ranges::copy_n copies a number of elements to a new location
   (C++20) (niebloid)
   ranges::copy_backward copies a range of elements in backwards order
   (C++20) (niebloid)
   ranges::move moves a range of elements to a new location
   (C++20) (niebloid)
   ranges::move_backward moves a range of elements to a new location in
   (C++20) backwards order
                        (niebloid)
   ranges::transform applies a function to a range of elements
   (C++20) (niebloid)
   ranges::replace_copy copies a range, replacing elements satisfying specific
   ranges::replace_copy_if criteria with another value
   (C++20) (niebloid)
   (C++20)
   ranges::remove_copy copies a range of elements omitting those that satisfy
   ranges::remove_copy_if specific criteria
   (C++20) (niebloid)
   (C++20)
   ranges::unique_copy creates a copy of some range of elements that contains
   (C++20) no consecutive duplicates
                        (niebloid)
   ranges::reverse_copy creates a copy of a range that is reversed
   (C++20) (niebloid)
   ranges::rotate_copy copies and rotate a range of elements
   (C++20) (niebloid)
   ranges::partial_sort_copy copies and partially sorts a range of elements
   (C++20) (niebloid)
   ranges::set_difference computes the difference between two sets
   (C++20) (niebloid)
         Memory functions
   ranges::uninitialized_copy copies a range of objects to an uninitialized area of
   (C++20) memory
                        (niebloid)
   ranges::uninitialized_copy_n copies a number of objects to an uninitialized area of
   (C++20) memory
                        (niebloid)
   ranges::uninitialized_move moves a range of objects to an uninitialized area of
   (C++20) memory
                        (niebloid)
   ranges::uninitialized_move_n moves a number of objects to an uninitialized area of
   (C++20) memory
                        (niebloid)

Synopsis
 namespace std::ranges
 {
     template<class I, class O>
     struct in_out_result
     {
         [[no_unique_address]] I in;
         [[no_unique_address]] O out;
         template<class I2, class O2>
         requires std::convertible_to<const I&, I2> && std::convertible_to<const O&, O2>
         constexpr operator in_out_result<I2, O2>() const &
         {
             return {in, out};
         }
         template<class I2, class O2>
         requires std::convertible_to<I, I2> && std::convertible_to<O, O2>
         constexpr operator in_out_result<I2, O2>() &&
         {
             return {std::move(in), std::move(out)};
         }
     };
 }

Notes
   Each standard library algorithm that uses this family of return types declares a new
   alias type, e.g. using merge_result = in_in_out_result<I1, I2, O>;.
   The names for such aliases are formed by adding the suffix "_result" to the
   algorithm's name. So, the return type of std::ranges::merge can be named as
   std::ranges::merge_result.
   Unlike std::pair and std::tuple, this class template has data members of meaningful
   names.

Example
// Run this code
 #include <algorithm>
 #include <array>
 #include <cctype>
 #include <iostream>
 #include <ranges>
 int main()
 {
     constexpr char in[] = "transform" "\n";
     std::array<char, sizeof(in)> out;
     const auto result = std::ranges::transform(in, out.begin(),
         [](char c) { return std::toupper(c); });
     auto print = [](char c) { std::cout << c; };
     std::ranges::for_each(std::cbegin(in), result.in, print);
     std::ranges::for_each(out.cbegin(), result.out, print);
 }

Output:
 transform
 TRANSFORM

See also
   pair implements binary tuple, i.e. a pair of values
           (class template)
   tuple implements fixed size container, which holds elements of possibly different
   (C++11) types
           (class template)