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

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Ranges library

Range access
begin cbegin end cend	rbegin crbegin rend crend	size ssize data cdata	empty
Range conversions
to (C++23)
Range primitives
range_size_trange_difference_t range_value_t	range_reference_trange_const_reference_trange_rvalue_reference_t   (C++23)	iterator_tconst_iterator_tsentinel_t (C++23)
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range    sized_range constant_range (C++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Factories
empty_viewviews::empty iota_viewviews::iota	single_viewviews::single basic_istream_viewviews::istream	repeat_viewviews::repeat (C++23)(C++23)
Adaptors
ref_view views::all_tviews::all common_viewviews::common owning_view views::counted reverse_viewviews::reverse zip_viewviews::zip (C++23)(C++23) as_const_viewviews::as_const (C++23)(C++23) as_rvalue_viewviews::as_rvalue (C++23)(C++23)	take_viewviews::take take_while_viewviews::take_while drop_viewviews::drop drop_while_viewviews::drop_while zip_transform_viewviews::zip_transform (C++23)(C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23)   cartesian_product_viewviews::cartesian_product (C++23)(C++23)	elements_viewviews::elements keys_viewviews::keys values_viewviews::values transform_viewviews::transform adjacent_viewviews::adjacent (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) stride_viewviews::stride (C++23)(C++23)	filter_viewviews::filter join_viewviews::join split_viewviews::split lazy_split_viewviews::lazy_split join_with_viewviews::join_with (C++23)(C++23) chunk_viewviews::chunk (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23)
Range adaptor objects
Range adaptor closure objects
Helper items
copyable-box	simple-view

 

std::ranges::transform_view

Member functions

transform_view::transform_view (C++20)

transform_view::base (C++20)

transform_view::begin (C++20)

transform_view::end (C++20)

transform_view::size (C++20)

Deduction guides

Iterator

transform_view::iterator::iterator (C++20)

transform_view::iterator::base (C++20)

transform_view::iterator::operator* (C++20)

transform_view::iterator::operator[] (C++20)

transform_view::iterator::operator++ transform_view::iterator::operator++(int) transform_view::iterator::operator-- transform_view::iterator::operator--(int) transform_view::iterator::operator+= transform_view::iterator::operator-= (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

operator==(transform_view::iterator) operator<(transform_view::iterator) operator>(transform_view::iterator) operator<=(transform_view::iterator) operator>=(transform_view::iterator) operator<=>(transform_view::iterator) (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

operator+(transform_view::iterator) operator-(transform_view::iterator) (C++20)(C++20)

iter_move(transform_view::iterator) (C++20)

Sentinel

transform_view::sentinel::sentinel (C++20)

transform_view::sentinel::base (C++20)

operator==(transform_view::iterator,transform_view::sentinel) (C++20)

operator-(transform_view::iterator,transform_view::sentinel) (C++20)

 

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