NAME¶

std::ranges::in_in_result - std::ranges::in_in_result

Synopsis¶

Defined in header <algorithm>
template< class I1, class I2 > (since C++20)
struct in_in_result;

ranges::in_in_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¶

I1, I2 - the types of the iterators that the ranges::in_in_result stores.

Data members

Member name Definition
in1 a value (that is supposed to be an iterator) of type I1.
(public member object)
in2 a value (that is supposed to be an iterator) of type I2.
(public member object)

All these members are declared with [[no_unique_address]] attribute.

Member functions¶

std::ranges::in_in_result::operator in_in_result<II1, II2>

template<class II1, class II2>

requires std::convertible_to<const I1&, II1> && std::convertible_to<const I2&, (1)
II2>

constexpr operator in_in_result<II1, II2>() const &;
template<class II1, class II2>

requires std::convertible_to<I1, II1> && std::convertible_to<I2, II2> (2)

constexpr operator in_in_result<II1, II2>() &&;

Converts *this to the result by constructing every data member of the result from
the corresponding member of *this.

1) Equivalent to return {in1, in2};.
2) Equivalent to return {std::move(in1), std::move(in2)};.

Standard library¶

The following standard library functions use ranges::in_in_result as the return
type:

Algorithm functions
ranges::mismatch finds the first position where two ranges differ
(C++20) (niebloid)
ranges::swap_ranges swaps two ranges of elements
(C++20) (niebloid)

Synopsis¶

namespace std::ranges
{
template<class I1, class I2>
struct in_in_result
{
[[no_unique_address]] I1 in1;
[[no_unique_address]] I2 in2;

template<class II1, class II2>
requires std::convertible_to<const I1&, II1> && std::convertible_to<const I2&, II2>
constexpr operator in_in_result<II1, II2>() const &
{
return {in1, in2};
}

template<class II1, class II2>
requires std::convertible_to<I1, II1> && std::convertible_to<I2, II2>
constexpr operator in_in_result<II1, II2>() &&
{
return {std::move(in1), std::move(in2)};
}
};
}

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 <iostream>
#include <ranges>

int main()
{
constexpr static auto in1 = {1, 2, 3, 4};
constexpr static auto in2 = {1, 2, 4, 5};

constexpr auto result {std::ranges::mismatch(in1, in2)};

static_assert(2 == std::ranges::distance(in1.begin(), result.in1));
static_assert(2 == std::ranges::distance(in2.begin(), result.in2));
}

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)