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std::ranges::transform_view<V,F>::iterator<Const>::base

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Ranges library
Range access
Range conversions
(C++23)

Range primitives



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(until C++23)(C++23)


 
 
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.

Contents

[edit] Parameters

(none)

[edit] Return value

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

[edit] Example

#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

[edit] 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 of the underlying iterator returns a reference
LWG 3593 C++20 the const& overload of base might not be noexcept made noexcept