NAME

std::ranges::transform_view::iterator::base - std::ranges::transform_view::iterator::base

Synopsis

constexpr const ranges::iterator_t<Base>& base() const & noexcept; (1) (since C++20)
constexpr ranges::iterator_t<Base> base() &&; (2) (since C++20)

Returns the underlying iterator.

1) Returns a reference to the underlying iterator.
2) Move constructs the result from the underlying iterator.

Parameters

(none)

Return value

1) A reference to the underlying iterator.
2) An iterator move constructed from the underlying iterator.

Example

// Run this code

#include <algorithm>
#include <iostream>
#include <iterator>
#include <ranges>

int main()
{
const auto v = { 0, 1, 2, 3, 4 };
auto x2 = [](int x) { return x << 1; };
std::ranges::transform_view tv{ v, x2 };
std::ostream_iterator<int> ostr{ std::cout, " " };

std::ranges::copy(v, ostr), std::cout << '\n';
std::ranges::copy(tv.base(), ostr), std::cout << '\n';
std::ranges::copy(tv, ostr), std::cout << '\n';
}

Output:

0 1 2 3 4
0 1 2 3 4
0 2 4 6 8

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3533 C++20 the const& overload of base returns a copy returns a reference
of the underlying iterator
LWG 3593 C++20 the const& overload of base might not be made noexcept
noexcept