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)