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[range.zip.iterator]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.iterator)
### 25.7.25 Zip view [[range.zip]](range.zip#iterator)
#### 25.7.25.3 Class template zip_view​::​*iterator* [range.zip.iterator]
[🔗](#lib:zip_view::iterator)
namespace std::ranges {template<[input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0)template<bool Const>class zip_view<Views...>::*iterator* { tuple<iterator_t<*maybe-const*<Const, Views>>...> *current_*; // *exposition only*constexpr explicit *iterator*(tuple<iterator_t<*maybe-const*<Const, Views>>...>); // *exposition only*public:using iterator_category = input_iterator_tag; // not always presentusing iterator_concept = *see below*; using value_type = tuple<range_value_t<*maybe-const*<Const, Views>>...>; using difference_type = common_type_t<range_difference_t<*maybe-const*<Const, Views>>...>; *iterator*() = default; constexpr *iterator*(*iterator*<!Const> i)requires Const && ([convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<iterator_t<Views>, iterator_t<const Views>> && ...); constexpr auto operator*() const; constexpr *iterator*& operator++(); constexpr void operator++(int); constexpr *iterator* operator++(int) requires [*all-forward*](range.adaptor.helpers#concept:all-forward "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; constexpr *iterator*& operator--() requires [*all-bidirectional*](range.adaptor.helpers#concept:all-bidirectional "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; constexpr *iterator* operator--(int) requires [*all-bidirectional*](range.adaptor.helpers#concept:all-bidirectional "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; constexpr *iterator*& operator+=(difference_type x)requires [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; constexpr *iterator*& operator-=(difference_type x)requires [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; constexpr auto operator[](difference_type n) constrequires [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; friend constexpr bool operator==(const *iterator*& x, const *iterator*& y)requires ([equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<iterator_t<*maybe-const*<Const, Views>>> && ...); friend constexpr auto operator<=>(const *iterator*& x, const *iterator*& y)requires [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; friend constexpr *iterator* operator+(const *iterator*& i, difference_type n)requires [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; friend constexpr *iterator* operator+(difference_type n, const *iterator*& i)requires [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; friend constexpr *iterator* operator-(const *iterator*& i, difference_type n)requires [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>; friend constexpr difference_type operator-(const *iterator*& x, const *iterator*& y)requires ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<iterator_t<*maybe-const*<Const, Views>>,
iterator_t<*maybe-const*<Const, Views>>> && ...); friend constexpr auto iter_move(const *iterator*& i) noexcept(*see below*); friend constexpr void iter_swap(const *iterator*& l, const *iterator*& r) noexcept(*see below*)requires ([indirectly_swappable](alg.req.ind.swap#concept:indirectly_swappable "24.3.7.4 Concept indirectly_­swappable [alg.req.ind.swap]")<iterator_t<*maybe-const*<Const, Views>>> && ...); };}
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11540)
*iterator*​::​iterator_concept is defined as follows:
- [(1.1)](#1.1)
If [*all-random-access*](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...> is modeled,
then iterator_concept denotes random_access_iterator_tag[.](#1.1.sentence-1)
- [(1.2)](#1.2)
Otherwise,
if [*all-bidirectional*](range.adaptor.helpers#concept:all-bidirectional "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...> is modeled,
then iterator_concept denotes bidirectional_iterator_tag[.](#1.2.sentence-1)
- [(1.3)](#1.3)
Otherwise,
if [*all-forward*](range.adaptor.helpers#concept:all-forward "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...> is modeled,
then iterator_concept denotes forward_iterator_tag[.](#1.3.sentence-1)
- [(1.4)](#1.4)
Otherwise, iterator_concept denotes input_iterator_tag[.](#1.4.sentence-1)
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11558)
*iterator*​::​iterator_category is present
if and only if [*all-forward*](range.adaptor.helpers#concept:all-forward "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...> is modeled[.](#2.sentence-1)
[3](#3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11562)
If the invocation of any non-const member function of *iterator* exits via an exception,
the iterator acquires a singular value[.](#3.sentence-1)
[🔗](#lib:zip_view::iterator,constructor)
`constexpr explicit iterator(tuple<iterator_t<maybe-const<Const, Views>>...> current);
`
[4](#4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11573)
*Effects*: Initializes *current_* with std​::​move(current)[.](#4.sentence-1)
[🔗](#lib:zip_view::iterator,constructor_)
`constexpr iterator(iterator<!Const> i)
requires Const && ([convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<iterator_t<Views>, iterator_t<const Views>> && ...);
`
[5](#5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11585)
*Effects*: Initializes *current_* with std​::​move(i.*current_*)[.](#5.sentence-1)
[🔗](#lib:operator*,izip_view::iterator)
`constexpr auto operator*() const;
`
[6](#6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11596)
*Effects*: Equivalent to:return *tuple-transform*([](auto& i) -> decltype(auto) { return *i; }, *current_*);
[🔗](#lib:operator++,izip_view::iterator)
`constexpr iterator& operator++();
`
[7](#7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11610)
*Effects*: Equivalent to:*tuple-for-each*([](auto& i) { ++i; }, *current_*);return *this;
[🔗](#lib:operator++,izip_view::iterator_)
`constexpr void operator++(int);
`
[8](#8)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11625)
*Effects*: Equivalent to ++*this[.](#8.sentence-1)
[🔗](#lib:operator++,izip_view::iterator__)
`constexpr iterator operator++(int) requires [all-forward](range.adaptor.helpers#concept:all-forward "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[9](#9)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11636)
*Effects*: Equivalent to:auto tmp = *this;++*this;return tmp;
[🔗](#lib:operator--,izip_view::iterator)
`constexpr iterator& operator--() requires [all-bidirectional](range.adaptor.helpers#concept:all-bidirectional "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[10](#10)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11652)
*Effects*: Equivalent to:*tuple-for-each*([](auto& i) { --i; }, *current_*);return *this;
[🔗](#lib:operator--,izip_view::iterator_)
`constexpr iterator operator--(int) requires [all-bidirectional](range.adaptor.helpers#concept:all-bidirectional "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[11](#11)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11667)
*Effects*: Equivalent to:auto tmp = *this;--*this;return tmp;
[🔗](#lib:operator+=,izip_view::iterator)
`constexpr iterator& operator+=(difference_type x)
requires [all-random-access](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[12](#12)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11684)
*Effects*: Equivalent to:*tuple-for-each*([&]<class I>(I& i) { i += iter_difference_t<I>(x); }, *current_*);return *this;
[🔗](#lib:operator-=,izip_view::iterator)
`constexpr iterator& operator-=(difference_type x)
requires [all-random-access](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[13](#13)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11700)
*Effects*: Equivalent to:*tuple-for-each*([&]<class I>(I& i) { i -= iter_difference_t<I>(x); }, *current_*);return *this;
[🔗](#lib:operator%5b%5d,izip_view::iterator)
`constexpr auto operator[](difference_type n) const
requires [all-random-access](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[14](#14)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11716)
*Effects*: Equivalent to:return *tuple-transform*([&]<class I>(I& i) -> decltype(auto) {return i[iter_difference_t<I>(n)];}, *current_*);
[🔗](#lib:operator==,izip_view::iterator)
`friend constexpr bool operator==(const iterator& x, const iterator& y)
requires ([equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<iterator_t<maybe-const<Const, Views>>> && ...);
`
[15](#15)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11733)
*Returns*:
- [(15.1)](#15.1)
x.*current_* == y.*current_* if [*all-bidirectional*](range.adaptor.helpers#concept:all-bidirectional "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...> is true[.](#15.1.sentence-1)
- [(15.2)](#15.2)
Otherwise, true if there exists an integer 0≤i<sizeof...(Views) such that bool(std​::​​get<i>(x.*current_*) == std​::​get<i>(y.*current_*)) is true[.](#15.2.sentence-1)
[*Note [1](#note-1)*:
This allows zip_view to model [common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]") when all constituent views model [common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")[.](#15.2.sentence-2)
— *end note*]
- [(15.3)](#15.3)
Otherwise, false[.](#15.3.sentence-1)
[🔗](#lib:operator%3c=%3e,izip_view::iterator)
`friend constexpr auto operator<=>(const iterator& x, const iterator& y)
requires [all-random-access](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[16](#16)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11760)
*Returns*: x.*current_* <=> y.*current_*[.](#16.sentence-1)
[🔗](#lib:operator+,izip_view::iterator)
`friend constexpr iterator operator+(const iterator& i, difference_type n)
requires [all-random-access](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
friend constexpr iterator operator+(difference_type n, const iterator& i)
requires [all-random-access](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[17](#17)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11774)
*Effects*: Equivalent to:auto r = i;
r += n;return r;
[🔗](#lib:operator-,izip_view::iterator)
`friend constexpr iterator operator-(const iterator& i, difference_type n)
requires [all-random-access](range.adaptor.helpers#concept:all-random-access "25.7.5 Range adaptor helpers [range.adaptor.helpers]")<Const, Views...>;
`
[18](#18)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11791)
*Effects*: Equivalent to:auto r = i;
r -= n;return r;
[🔗](#lib:operator-,izip_view::iterator_)
`friend constexpr difference_type operator-(const iterator& x, const iterator& y)
requires ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<iterator_t<maybe-const<Const, Views>>,
iterator_t<maybe-const<Const, Views>>> && ...);
`
[19](#19)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11809)
Let *DIST*(i) be difference_type(std​::​get<i>(x.*current_*) - std​::​get<i>(y.*current_*))[.](#19.sentence-1)
[20](#20)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11812)
*Returns*: The value with the smallest absolute value among *DIST*(n) for all integers 0≤n<sizeof...(Views)[.](#20.sentence-1)
[🔗](#lib:iter_move,izip_view::iterator)
`friend constexpr auto iter_move(const iterator& i) noexcept(see below);
`
[21](#21)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11824)
*Effects*: Equivalent to:return *tuple-transform*(ranges::iter_move, i.*current_*);
[22](#22)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11831)
*Remarks*: The exception specification is equivalent to:(noexcept(ranges::iter_move(declval<const iterator_t<*maybe-const*<Const,
Views>>&>())) && ...) &&(is_nothrow_move_constructible_v<range_rvalue_reference_t<*maybe-const*<Const,
Views>>> && ...)
[🔗](#lib:iter_swap,izip_view::iterator)
`friend constexpr void iter_swap(const iterator& l, const iterator& r) noexcept(see below)
requires ([indirectly_swappable](alg.req.ind.swap#concept:indirectly_swappable "24.3.7.4 Concept indirectly_­swappable [alg.req.ind.swap]")<iterator_t<maybe-const<Const, Views>>> && ...);
`
[23](#23)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11849)
*Effects*: For every integer 0≤i<sizeof...(Views),
performs:ranges::iter_swap(std::get<i>(l.*current_*), std::get<i>(r.*current_*))
[24](#24)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11857)
*Remarks*: The exception specification is equivalent to
the logical and of the following expressions:noexcept(ranges::iter_swap(std::get<i>(l.*current_*), std::get<i>(r.*current_*))) for every integer 0≤i<sizeof...(Views)[.](#24.sentence-1)

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[range.zip.overview]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.overview)
### 25.7.25 Zip view [[range.zip]](range.zip#overview)
#### 25.7.25.1 Overview [range.zip.overview]
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11340)
zip_view takes any number of views and
produces a view of tuples of references
to the corresponding elements of the constituent views[.](#1.sentence-1)
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11346)
The name views​::​zip denotes
a customization point object ([[customization.point.object]](customization.point.object "16.3.3.3.5 Customization Point Object types"))[.](#2.sentence-1)
Given a pack of subexpressions Es...,
the expression views​::​zip(Es...) is expression-equivalent to
- [(2.1)](#2.1)
auto(views​::​empty<tuple<>>) if Es is an empty pack,
- [(2.2)](#2.2)
otherwise, zip_view<views​::​all_t<decltype((Es))>...>(Es...)[.](#2.sentence-2)
[*Example [1](#example-1)*: vector v = {1, 2};
list l = {'a', 'b', 'c'};
auto z = views::zip(v, l);
range_reference_t<decltype(z)> f = z.front(); // f is a tuple<int&, char&>// that refers to the first element of v and lfor (auto&& [x, y] : z) { cout << '(' << x << ", " << y << ") "; // prints (1, a) (2, b)} — *end example*]

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[range.zip.sentinel]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.sentinel)
### 25.7.25 Zip view [[range.zip]](range.zip#sentinel)
#### 25.7.25.4 Class template zip_view​::​*sentinel* [range.zip.sentinel]
[🔗](#lib:zip_view::sentinel)
namespace std::ranges {template<[input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0)template<bool Const>class zip_view<Views...>::*sentinel* { tuple<sentinel_t<*maybe-const*<Const, Views>>...> *end_*; // *exposition only*constexpr explicit *sentinel*(tuple<sentinel_t<*maybe-const*<Const, Views>>...> end); // *exposition only*public:*sentinel*() = default; constexpr *sentinel*(*sentinel*<!Const> i)requires Const && ([convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<sentinel_t<Views>, sentinel_t<const Views>> && ...); template<bool OtherConst>requires ([sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<sentinel_t<*maybe-const*<Const, Views>>,
iterator_t<*maybe-const*<OtherConst, Views>>> && ...)friend constexpr bool operator==(const *iterator*<OtherConst>& x, const *sentinel*& y); template<bool OtherConst>requires ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<*maybe-const*<Const, Views>>,
iterator_t<*maybe-const*<OtherConst, Views>>> && ...)friend constexpr common_type_t<range_difference_t<*maybe-const*<OtherConst, Views>>...>operator-(const *iterator*<OtherConst>& x, const *sentinel*& y); template<bool OtherConst>requires ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<*maybe-const*<Const, Views>>,
iterator_t<*maybe-const*<OtherConst, Views>>> && ...)friend constexpr common_type_t<range_difference_t<*maybe-const*<OtherConst, Views>>...>operator-(const *sentinel*& y, const *iterator*<OtherConst>& x); };}
[🔗](#lib:zip_view::sentinel,constructor)
`constexpr explicit sentinel(tuple<sentinel_t<maybe-const<Const, Views>>...> end);
`
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11910)
*Effects*: Initializes *end_* with end[.](#1.sentence-1)
[🔗](#lib:zip_view::sentinel,constructor_)
`constexpr sentinel(sentinel<!Const> i)
requires Const && ([convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<sentinel_t<Views>, sentinel_t<const Views>> && ...);
`
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11922)
*Effects*: Initializes *end_* with std​::​move(i.*end_*)[.](#2.sentence-1)
[🔗](#lib:operator==,zip_view::sentinel)
`template<bool OtherConst>
requires ([sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<sentinel_t<maybe-const<Const, Views>>,
iterator_t<maybe-const<OtherConst, Views>>> && ...)
friend constexpr bool operator==(const iterator<OtherConst>& x, const sentinel& y);
`
[3](#3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11936)
*Returns*: true if there exists an integer 0≤i<sizeof...(Views) such that bool(std​::​get<i>(x.​*current_*) == std​::​get<i>(y.*end_*)) is true[.](#3.sentence-1)
Otherwise, false[.](#3.sentence-2)
[🔗](#lib:operator-,zip_view::sentinel)
`template<bool OtherConst>
requires ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<maybe-const<Const, Views>>,
iterator_t<maybe-const<OtherConst, Views>>> && ...)
friend constexpr common_type_t<range_difference_t<maybe-const<OtherConst, Views>>...>
operator-(const iterator<OtherConst>& x, const sentinel& y);
`
[4](#4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11954)
Let D be the return type[.](#4.sentence-1)
Let *DIST*(i) beD(std​::​get<i>(x.*current_*) - std​::​get<i>(y.*end_*))[.](#4.sentence-2)
[5](#5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11959)
*Returns*: The value with the smallest absolute value among *DIST*(n) for all integers 0≤n<sizeof...(Views)[.](#5.sentence-1)
[🔗](#lib:operator-,zip_view::sentinel_)
`template<bool OtherConst>
requires ([sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<sentinel_t<maybe-const<Const, Views>>,
iterator_t<maybe-const<OtherConst, Views>>> && ...)
friend constexpr common_type_t<range_difference_t<maybe-const<OtherConst, Views>>...>
operator-(const sentinel& y, const iterator<OtherConst>& x);
`
[6](#6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11975)
*Effects*: Equivalent to: return -(x - y);

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[range.zip.transform]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.transform)
### 25.7.26 Zip transform view [range.zip.transform]
#### [25.7.26.1](#overview) Overview [[range.zip.transform.overview]](range.zip.transform.overview)
[1](#overview-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11984)
zip_transform_view takes an invocable object and
any number of views and
produces a view
whose Mth element is
the result of applying the invocable object
to the Mth elements of all views[.](#overview-1.sentence-1)
[2](#overview-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11993)
The name views​::​zip_transform denotes
a customization point object ([[customization.point.object]](customization.point.object "16.3.3.3.5 Customization Point Object types"))[.](#overview-2.sentence-1)
Let F be a subexpression, and
let Es... be a pack of subexpressions[.](#overview-2.sentence-2)
- [(2.1)](#overview-2.1)
If Es is an empty pack,
let FD be decay_t<decltype((F))>[.](#overview-2.1.sentence-1)
* [(2.1.1)](#overview-2.1.1)
If [move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]")<FD> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<FD&> is false, or
if decay_t<invoke_result_t<FD&>> is not an object type,views​::​zip_transform(F, Es...) is ill-formed.
* [(2.1.2)](#overview-2.1.2)
Otherwise, the expression views​::​zip_transform(F, Es...) is expression-equivalent to((void)F, auto(views::empty<decay_t<invoke_result_t<FD&>>>))
- [(2.2)](#overview-2.2)
Otherwise, the expression views​::​zip_transform(F, Es...) is expression-equivalent to zip_transform_view(F, Es...)[.](#overview-2.2.sentence-1)
[3](#overview-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12021)
[*Example [1](#overview-example-1)*: vector v1 = {1, 2};
vector v2 = {4, 5, 6};
for (auto i : views::zip_transform(plus(), v1, v2)) { cout << i << ' '; // prints 5 7} — *end example*]
#### [25.7.26.2](#view) Class template zip_transform_view [[range.zip.transform.view]](range.zip.transform.view)
[🔗](#lib:zip_transform_view_)
namespace std::ranges {template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") F, [input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<F&, range_reference_t<Views>...> &&[*can-reference*](iterator.synopsis#concept:can-reference "24.2 Header <iterator>&nbsp;synopsis [iterator.synopsis]")<invoke_result_t<F&, range_reference_t<Views>...>>class zip_transform_view : public view_interface<zip_transform_view<F, Views...>> {*movable-box*<F> *fun_*; // *exposition only* zip_view<Views...> *zip_*; // *exposition only*using *InnerView* = zip_view<Views...>; // *exposition only*template<bool Const>using *ziperator* = iterator_t<*maybe-const*<Const, *InnerView*>>; // *exposition only*template<bool Const>using *zentinel* = sentinel_t<*maybe-const*<Const, *InnerView*>>; // *exposition only*// [[range.zip.transform.iterator]](#iterator "25.7.26.3 Class template zip_­transform_­view​::​iterator"), class template zip_transform_view​::​*iterator*template<bool> class *iterator*; // *exposition only*// [[range.zip.transform.sentinel]](#sentinel "25.7.26.4 Class template zip_­transform_­view​::​sentinel"), class template zip_transform_view​::​*sentinel*template<bool> class *sentinel*; // *exposition only*public: zip_transform_view() = default; constexpr explicit zip_transform_view(F fun, Views... views); constexpr auto begin() { return *iterator*<false>(*this, *zip_*.begin()); }constexpr auto begin() constrequires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const *InnerView*> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<const F&, range_reference_t<const Views>...> {return *iterator*<true>(*this, *zip_*.begin()); }constexpr auto end() {if constexpr ([common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<*InnerView*>) {return *iterator*<false>(*this, *zip_*.end()); } else {return *sentinel*<false>(*zip_*.end()); }}constexpr auto end() constrequires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const *InnerView*> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<const F&, range_reference_t<const Views>...> {if constexpr ([common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<const *InnerView*>) {return *iterator*<true>(*this, *zip_*.end()); } else {return *sentinel*<true>(*zip_*.end()); }}constexpr auto size() requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<*InnerView*> {return *zip_*.size(); }constexpr auto size() const requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const *InnerView*> {return *zip_*.size(); }}; template<class F, class... Rs> zip_transform_view(F, Rs&&...) -> zip_transform_view<F, views::all_t<Rs>...>;}
[🔗](#lib:zip_transform_view,constructor)
`constexpr explicit zip_transform_view(F fun, Views... views);
`
[1](#view-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12112)
*Effects*: Initializes *fun_* with std​::​move(fun) and*zip_* with std​::​move(views)...[.](#view-1.sentence-1)
#### [25.7.26.3](#iterator) Class template zip_transform_view​::​*iterator* [[range.zip.transform.iterator]](range.zip.transform.iterator)
[🔗](#lib:zip_transform_view::iterator)
namespace std::ranges {template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") F, [input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<F&, range_reference_t<Views>...> &&[*can-reference*](iterator.synopsis#concept:can-reference "24.2 Header <iterator>&nbsp;synopsis [iterator.synopsis]")<invoke_result_t<F&, range_reference_t<Views>...>>template<bool Const>class zip_transform_view<F, Views...>::*iterator* {using *Parent* = *maybe-const*<Const, zip_transform_view>; // *exposition only*using *Base* = *maybe-const*<Const, *InnerView*>; // *exposition only**Parent** *parent_* = nullptr; // *exposition only**ziperator*<Const> *inner_*; // *exposition only*constexpr *iterator*(*Parent*& parent, *ziperator*<Const> inner); // *exposition only*public:using iterator_category = *see below*; // not always presentusing iterator_concept = typename *ziperator*<Const>::iterator_concept; using value_type = remove_cvref_t<invoke_result_t<*maybe-const*<Const, F>&,
range_reference_t<*maybe-const*<Const, Views>>...>>; using difference_type = range_difference_t<*Base*>; *iterator*() = default; constexpr *iterator*(*iterator*<!Const> i)requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<*ziperator*<false>, *ziperator*<Const>>; constexpr decltype(auto) operator*() const noexcept(*see below*); constexpr *iterator*& operator++(); constexpr void operator++(int); constexpr *iterator* operator++(int) requires [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator*& operator--() requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator* operator--(int) requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator*& operator+=(difference_type x) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator*& operator-=(difference_type x) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr decltype(auto) operator[](difference_type n) constrequires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr bool operator==(const *iterator*& x, const *iterator*& y)requires [equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<*ziperator*<Const>>; friend constexpr auto operator<=>(const *iterator*& x, const *iterator*& y)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr *iterator* operator+(const *iterator*& i, difference_type n)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr *iterator* operator+(difference_type n, const *iterator*& i)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr *iterator* operator-(const *iterator*& i, difference_type n)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr difference_type operator-(const *iterator*& x, const *iterator*& y)requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<*ziperator*<Const>, *ziperator*<Const>>; };}
[1](#iterator-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12180)
The member [*typedef-name*](dcl.typedef#nt:typedef-name "9.2.4 The typedef specifier [dcl.typedef]")*iterator*​::​iterator_category is defined if and only if *Base* models [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")[.](#iterator-1.sentence-1)
In that case,*iterator*​::​iterator_category is defined as follows:
- [(1.1)](#iterator-1.1)
Ifinvoke_result_t<*maybe-const*<Const, F>&, range_reference_t<*maybe-const*<Const, Views>>...> is not a reference,iterator_category denotes input_iterator_tag.
- [(1.2)](#iterator-1.2)
Otherwise, let Cs denote the pack of typesiterator_traits<iterator_t<*maybe-const*<Const, Views>>>​::​iterator_category.... * [(1.2.1)](#iterator-1.2.1)
If ([derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_­from [concept.derived]")<Cs, random_access_iterator_tag> && ...) is true,iterator_category denotes random_access_iterator_tag[.](#iterator-1.2.1.sentence-1)
* [(1.2.2)](#iterator-1.2.2)
Otherwise,
if ([derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_­from [concept.derived]")<Cs, bidirectional_iterator_tag> && ...) is true,iterator_category denotes bidirectional_iterator_tag[.](#iterator-1.2.2.sentence-1)
* [(1.2.3)](#iterator-1.2.3)
Otherwise,
if ([derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_­from [concept.derived]")<Cs, forward_iterator_tag> && ...) is true,iterator_category denotes forward_iterator_tag[.](#iterator-1.2.3.sentence-1)
* [(1.2.4)](#iterator-1.2.4)
Otherwise, iterator_category denotes input_iterator_tag[.](#iterator-1.2.4.sentence-1)
[🔗](#lib:zip_transform_view::iterator,constructor)
`constexpr iterator(Parent& parent, ziperator<Const> inner);
`
[2](#iterator-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12223)
*Effects*: Initializes *parent_* with addressof(parent) and*inner_* with std​::​move(inner)[.](#iterator-2.sentence-1)
[🔗](#lib:zip_transform_view::iterator,constructor_)
`constexpr iterator(iterator<!Const> i)
requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<ziperator<false>, ziperator<Const>>;
`
[3](#iterator-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12236)
*Effects*: Initializes *parent_* with i.*parent_* and*inner_* with std​::​move(i.*inner_*)[.](#iterator-3.sentence-1)
[🔗](#lib:operator*,zip_transform_view::iterator)
`constexpr decltype(auto) operator*() const noexcept(see below);
`
[4](#iterator-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12248)
*Effects*: Equivalent to:return apply([&](const auto&... iters) -> decltype(auto) {return invoke(**parent_*->*fun_*, *iters...);}, *inner_*.*current_*);
[5](#iterator-5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12257)
*Remarks*: Let Is be the pack 0, 1, …, (sizeof...(Views) - 1)[.](#iterator-5.sentence-1)
The exception specification is equivalent to:noexcept(invoke(**parent_*->*fun_*, *std​::​get<Is>(*inner_*.*current_*)...))[.](#iterator-5.sentence-2)
[🔗](#lib:operator++,zip_transform_view::iterator)
`constexpr iterator& operator++();
`
[6](#iterator-6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12270)
*Effects*: Equivalent to:++*inner_*;return *this;
[🔗](#lib:operator++,zip_transform_view::iterator_)
`constexpr void operator++(int);
`
[7](#iterator-7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12285)
*Effects*: Equivalent to: ++*this[.](#iterator-7.sentence-1)
[🔗](#lib:operator++,zip_transform_view::iterator__)
`constexpr iterator operator++(int) requires [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[8](#iterator-8)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12296)
*Effects*: Equivalent to:auto tmp = *this;++*this;return tmp;
[🔗](#lib:operator--,zip_transform_view::iterator)
`constexpr iterator& operator--() requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[9](#iterator-9)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12312)
*Effects*: Equivalent to:--*inner_*;return *this;
[🔗](#lib:operator--,zip_transform_view::iterator_)
`constexpr iterator operator--(int) requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[10](#iterator-10)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12327)
*Effects*: Equivalent to:auto tmp = *this;--*this;return tmp;
[🔗](#lib:operator+=,zip_transform_view::iterator)
`constexpr iterator& operator+=(difference_type x)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[11](#iterator-11)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12344)
*Effects*: Equivalent to:*inner_* += x;return *this;
[🔗](#lib:operator+=,zip_transform_view::iterator_)
`constexpr iterator& operator-=(difference_type x)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[12](#iterator-12)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12360)
*Effects*: Equivalent to:*inner_* -= x;return *this;
[🔗](#lib:operator%5b%5d,zip_transform_view::iterator)
`constexpr decltype(auto) operator[](difference_type n) const
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[13](#iterator-13)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12376)
*Effects*: Equivalent to:return apply([&]<class... Is>(const Is&... iters) -> decltype(auto) {return invoke(**parent_*->*fun_*, iters[iter_difference_t<Is>(n)]...);}, *inner_*.*current_*);
[🔗](#lib:operator==,zip_transform_view::iterator)
`friend constexpr bool operator==(const iterator& x, const iterator& y)
requires [equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<ziperator<Const>>;
friend constexpr auto operator<=>(const iterator& x, const iterator& y)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[14](#iterator-14)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12395)
Let *op* be the operator[.](#iterator-14.sentence-1)
[15](#iterator-15)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12398)
*Effects*: Equivalent to:return x.*inner_* *op* y.*inner_*;
[🔗](#lib:operator+,zip_transform_view::iterator)
`friend constexpr iterator operator+(const iterator& i, difference_type n)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
friend constexpr iterator operator+(difference_type n, const iterator& i)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[16](#iterator-16)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12413)
*Effects*: Equivalent to:return *iterator*(*i.*parent_*, i.*inner_* + n);
[🔗](#lib:operator-,zip_transform_view::iterator)
`friend constexpr iterator operator-(const iterator& i, difference_type n)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[17](#iterator-17)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12426)
*Effects*: Equivalent to:return *iterator*(*i.*parent_*, i.*inner_* - n);
[🔗](#lib:operator-,zip_transform_view::iterator_)
`friend constexpr difference_type operator-(const iterator& x, const iterator& y)
requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<ziperator<Const>, ziperator<Const>>;
`
[18](#iterator-18)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12439)
*Effects*: Equivalent to:return x.*inner_* - y.*inner_*;
#### [25.7.26.4](#sentinel) Class template zip_transform_view​::​*sentinel* [[range.zip.transform.sentinel]](range.zip.transform.sentinel)
[🔗](#lib:zip_transform_view::sentinel)
namespace std::ranges {template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") F, [input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<F&, range_reference_t<Views>...> &&[*can-reference*](iterator.synopsis#concept:can-reference "24.2 Header <iterator>&nbsp;synopsis [iterator.synopsis]")<invoke_result_t<F&, range_reference_t<Views>...>>template<bool Const>class zip_transform_view<F, Views...>::*sentinel* {*zentinel*<Const> *inner_*; // *exposition only*constexpr explicit *sentinel*(*zentinel*<Const> inner); // *exposition only*public:*sentinel*() = default; constexpr *sentinel*(*sentinel*<!Const> i)requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<*zentinel*<false>, *zentinel*<Const>>; template<bool OtherConst>requires [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<*zentinel*<Const>, *ziperator*<OtherConst>>friend constexpr bool operator==(const *iterator*<OtherConst>& x, const *sentinel*& y); template<bool OtherConst>requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<*zentinel*<Const>, *ziperator*<OtherConst>>friend constexpr range_difference_t<*maybe-const*<OtherConst, *InnerView*>>operator-(const *iterator*<OtherConst>& x, const *sentinel*& y); template<bool OtherConst>requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<*zentinel*<Const>, *ziperator*<OtherConst>>friend constexpr range_difference_t<*maybe-const*<OtherConst, *InnerView*>>operator-(const *sentinel*& x, const *iterator*<OtherConst>& y); };}
[🔗](#lib:zip_transform_view::sentinel,constructor)
`constexpr explicit sentinel(zentinel<Const> inner);
`
[1](#sentinel-1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12487)
*Effects*: Initializes *inner_* with inner[.](#sentinel-1.sentence-1)
[🔗](#lib:zip_transform_view::sentinel,constructor_)
`constexpr sentinel(sentinel<!Const> i)
requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<zentinel<false>, zentinel<Const>>;
`
[2](#sentinel-2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12499)
*Effects*: Initializes *inner_* with std​::​move(i.*inner_*)[.](#sentinel-2.sentence-1)
[🔗](#lib:operator==,zip_transform_view::sentinel)
`template<bool OtherConst>
requires [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<zentinel<Const>, ziperator<OtherConst>>
friend constexpr bool operator==(const iterator<OtherConst>& x, const sentinel& y);
`
[3](#sentinel-3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12512)
*Effects*: Equivalent to: return x.*inner_* == y.*inner_*;
[🔗](#lib:operator-,zip_transform_view::sentinel)
`template<bool OtherConst>
requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<zentinel<Const>, ziperator<OtherConst>>
friend constexpr range_difference_t<maybe-const<OtherConst, InnerView>>
operator-(const iterator<OtherConst>& x, const sentinel& y);
template<bool OtherConst>
requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<zentinel<Const>, ziperator<OtherConst>>
friend constexpr range_difference_t<maybe-const<OtherConst, InnerView>>
operator-(const sentinel& x, const iterator<OtherConst>& y);
`
[4](#sentinel-4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12530)
*Effects*: Equivalent to: return x.*inner_* - y.*inner_*;

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[range.zip.transform.iterator]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.transform.iterator)
### 25.7.26 Zip transform view [[range.zip.transform]](range.zip.transform#iterator)
#### 25.7.26.3 Class template zip_transform_view​::​*iterator* [range.zip.transform.iterator]
[🔗](#lib:zip_transform_view::iterator)
namespace std::ranges {template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") F, [input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<F&, range_reference_t<Views>...> &&[*can-reference*](iterator.synopsis#concept:can-reference "24.2 Header <iterator>&nbsp;synopsis [iterator.synopsis]")<invoke_result_t<F&, range_reference_t<Views>...>>template<bool Const>class zip_transform_view<F, Views...>::*iterator* {using *Parent* = *maybe-const*<Const, zip_transform_view>; // *exposition only*using *Base* = *maybe-const*<Const, *InnerView*>; // *exposition only**Parent** *parent_* = nullptr; // *exposition only**ziperator*<Const> *inner_*; // *exposition only*constexpr *iterator*(*Parent*& parent, *ziperator*<Const> inner); // *exposition only*public:using iterator_category = *see below*; // not always presentusing iterator_concept = typename *ziperator*<Const>::iterator_concept; using value_type = remove_cvref_t<invoke_result_t<*maybe-const*<Const, F>&,
range_reference_t<*maybe-const*<Const, Views>>...>>; using difference_type = range_difference_t<*Base*>; *iterator*() = default; constexpr *iterator*(*iterator*<!Const> i)requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<*ziperator*<false>, *ziperator*<Const>>; constexpr decltype(auto) operator*() const noexcept(*see below*); constexpr *iterator*& operator++(); constexpr void operator++(int); constexpr *iterator* operator++(int) requires [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator*& operator--() requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator* operator--(int) requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator*& operator+=(difference_type x) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr *iterator*& operator-=(difference_type x) requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; constexpr decltype(auto) operator[](difference_type n) constrequires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr bool operator==(const *iterator*& x, const *iterator*& y)requires [equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<*ziperator*<Const>>; friend constexpr auto operator<=>(const *iterator*& x, const *iterator*& y)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr *iterator* operator+(const *iterator*& i, difference_type n)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr *iterator* operator+(difference_type n, const *iterator*& i)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr *iterator* operator-(const *iterator*& i, difference_type n)requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<*Base*>; friend constexpr difference_type operator-(const *iterator*& x, const *iterator*& y)requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<*ziperator*<Const>, *ziperator*<Const>>; };}
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12180)
The member [*typedef-name*](dcl.typedef#nt:typedef-name "9.2.4 The typedef specifier [dcl.typedef]")*iterator*​::​iterator_category is defined if and only if *Base* models [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")[.](#1.sentence-1)
In that case,*iterator*​::​iterator_category is defined as follows:
- [(1.1)](#1.1)
Ifinvoke_result_t<*maybe-const*<Const, F>&, range_reference_t<*maybe-const*<Const, Views>>...> is not a reference,iterator_category denotes input_iterator_tag.
- [(1.2)](#1.2)
Otherwise, let Cs denote the pack of typesiterator_traits<iterator_t<*maybe-const*<Const, Views>>>​::​iterator_category.... * [(1.2.1)](#1.2.1)
If ([derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_­from [concept.derived]")<Cs, random_access_iterator_tag> && ...) is true,iterator_category denotes random_access_iterator_tag[.](#1.2.1.sentence-1)
* [(1.2.2)](#1.2.2)
Otherwise,
if ([derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_­from [concept.derived]")<Cs, bidirectional_iterator_tag> && ...) is true,iterator_category denotes bidirectional_iterator_tag[.](#1.2.2.sentence-1)
* [(1.2.3)](#1.2.3)
Otherwise,
if ([derived_from](concept.derived#concept:derived_from "18.4.3 Concept derived_­from [concept.derived]")<Cs, forward_iterator_tag> && ...) is true,iterator_category denotes forward_iterator_tag[.](#1.2.3.sentence-1)
* [(1.2.4)](#1.2.4)
Otherwise, iterator_category denotes input_iterator_tag[.](#1.2.4.sentence-1)
[🔗](#lib:zip_transform_view::iterator,constructor)
`constexpr iterator(Parent& parent, ziperator<Const> inner);
`
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12223)
*Effects*: Initializes *parent_* with addressof(parent) and*inner_* with std​::​move(inner)[.](#2.sentence-1)
[🔗](#lib:zip_transform_view::iterator,constructor_)
`constexpr iterator(iterator<!Const> i)
requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<ziperator<false>, ziperator<Const>>;
`
[3](#3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12236)
*Effects*: Initializes *parent_* with i.*parent_* and*inner_* with std​::​move(i.*inner_*)[.](#3.sentence-1)
[🔗](#lib:operator*,zip_transform_view::iterator)
`constexpr decltype(auto) operator*() const noexcept(see below);
`
[4](#4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12248)
*Effects*: Equivalent to:return apply([&](const auto&... iters) -> decltype(auto) {return invoke(**parent_*->*fun_*, *iters...);}, *inner_*.*current_*);
[5](#5)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12257)
*Remarks*: Let Is be the pack 0, 1, …, (sizeof...(Views) - 1)[.](#5.sentence-1)
The exception specification is equivalent to:noexcept(invoke(**parent_*->*fun_*, *std​::​get<Is>(*inner_*.*current_*)...))[.](#5.sentence-2)
[🔗](#lib:operator++,zip_transform_view::iterator)
`constexpr iterator& operator++();
`
[6](#6)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12270)
*Effects*: Equivalent to:++*inner_*;return *this;
[🔗](#lib:operator++,zip_transform_view::iterator_)
`constexpr void operator++(int);
`
[7](#7)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12285)
*Effects*: Equivalent to: ++*this[.](#7.sentence-1)
[🔗](#lib:operator++,zip_transform_view::iterator__)
`constexpr iterator operator++(int) requires [forward_range](range.refinements#concept:forward_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[8](#8)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12296)
*Effects*: Equivalent to:auto tmp = *this;++*this;return tmp;
[🔗](#lib:operator--,zip_transform_view::iterator)
`constexpr iterator& operator--() requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[9](#9)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12312)
*Effects*: Equivalent to:--*inner_*;return *this;
[🔗](#lib:operator--,zip_transform_view::iterator_)
`constexpr iterator operator--(int) requires [bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[10](#10)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12327)
*Effects*: Equivalent to:auto tmp = *this;--*this;return tmp;
[🔗](#lib:operator+=,zip_transform_view::iterator)
`constexpr iterator& operator+=(difference_type x)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[11](#11)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12344)
*Effects*: Equivalent to:*inner_* += x;return *this;
[🔗](#lib:operator+=,zip_transform_view::iterator_)
`constexpr iterator& operator-=(difference_type x)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[12](#12)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12360)
*Effects*: Equivalent to:*inner_* -= x;return *this;
[🔗](#lib:operator%5b%5d,zip_transform_view::iterator)
`constexpr decltype(auto) operator[](difference_type n) const
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[13](#13)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12376)
*Effects*: Equivalent to:return apply([&]<class... Is>(const Is&... iters) -> decltype(auto) {return invoke(**parent_*->*fun_*, iters[iter_difference_t<Is>(n)]...);}, *inner_*.*current_*);
[🔗](#lib:operator==,zip_transform_view::iterator)
`friend constexpr bool operator==(const iterator& x, const iterator& y)
requires [equality_comparable](concept.equalitycomparable#concept:equality_comparable "18.5.4 Concept equality_­comparable [concept.equalitycomparable]")<ziperator<Const>>;
friend constexpr auto operator<=>(const iterator& x, const iterator& y)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[14](#14)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12395)
Let *op* be the operator[.](#14.sentence-1)
[15](#15)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12398)
*Effects*: Equivalent to:return x.*inner_* *op* y.*inner_*;
[🔗](#lib:operator+,zip_transform_view::iterator)
`friend constexpr iterator operator+(const iterator& i, difference_type n)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
friend constexpr iterator operator+(difference_type n, const iterator& i)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[16](#16)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12413)
*Effects*: Equivalent to:return *iterator*(*i.*parent_*, i.*inner_* + n);
[🔗](#lib:operator-,zip_transform_view::iterator)
`friend constexpr iterator operator-(const iterator& i, difference_type n)
requires [random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Base>;
`
[17](#17)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12426)
*Effects*: Equivalent to:return *iterator*(*i.*parent_*, i.*inner_* - n);
[🔗](#lib:operator-,zip_transform_view::iterator_)
`friend constexpr difference_type operator-(const iterator& x, const iterator& y)
requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<ziperator<Const>, ziperator<Const>>;
`
[18](#18)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12439)
*Effects*: Equivalent to:return x.*inner_* - y.*inner_*;

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[range.zip.transform.overview]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.transform.overview)
### 25.7.26 Zip transform view [[range.zip.transform]](range.zip.transform#overview)
#### 25.7.26.1 Overview [range.zip.transform.overview]
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11984)
zip_transform_view takes an invocable object and
any number of views and
produces a view
whose Mth element is
the result of applying the invocable object
to the Mth elements of all views[.](#1.sentence-1)
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11993)
The name views​::​zip_transform denotes
a customization point object ([[customization.point.object]](customization.point.object "16.3.3.3.5 Customization Point Object types"))[.](#2.sentence-1)
Let F be a subexpression, and
let Es... be a pack of subexpressions[.](#2.sentence-2)
- [(2.1)](#2.1)
If Es is an empty pack,
let FD be decay_t<decltype((F))>[.](#2.1.sentence-1)
* [(2.1.1)](#2.1.1)
If [move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]")<FD> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<FD&> is false, or
if decay_t<invoke_result_t<FD&>> is not an object type,views​::​zip_transform(F, Es...) is ill-formed.
* [(2.1.2)](#2.1.2)
Otherwise, the expression views​::​zip_transform(F, Es...) is expression-equivalent to((void)F, auto(views::empty<decay_t<invoke_result_t<FD&>>>))
- [(2.2)](#2.2)
Otherwise, the expression views​::​zip_transform(F, Es...) is expression-equivalent to zip_transform_view(F, Es...)[.](#2.2.sentence-1)
[3](#3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12021)
[*Example [1](#example-1)*: vector v1 = {1, 2};
vector v2 = {4, 5, 6};
for (auto i : views::zip_transform(plus(), v1, v2)) { cout << i << ' '; // prints 5 7} — *end example*]

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[range.zip.transform.sentinel]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.transform.sentinel)
### 25.7.26 Zip transform view [[range.zip.transform]](range.zip.transform#sentinel)
#### 25.7.26.4 Class template zip_transform_view​::​*sentinel* [range.zip.transform.sentinel]
[🔗](#lib:zip_transform_view::sentinel)
namespace std::ranges {template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") F, [input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<F&, range_reference_t<Views>...> &&[*can-reference*](iterator.synopsis#concept:can-reference "24.2 Header <iterator>&nbsp;synopsis [iterator.synopsis]")<invoke_result_t<F&, range_reference_t<Views>...>>template<bool Const>class zip_transform_view<F, Views...>::*sentinel* {*zentinel*<Const> *inner_*; // *exposition only*constexpr explicit *sentinel*(*zentinel*<Const> inner); // *exposition only*public:*sentinel*() = default; constexpr *sentinel*(*sentinel*<!Const> i)requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<*zentinel*<false>, *zentinel*<Const>>; template<bool OtherConst>requires [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<*zentinel*<Const>, *ziperator*<OtherConst>>friend constexpr bool operator==(const *iterator*<OtherConst>& x, const *sentinel*& y); template<bool OtherConst>requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<*zentinel*<Const>, *ziperator*<OtherConst>>friend constexpr range_difference_t<*maybe-const*<OtherConst, *InnerView*>>operator-(const *iterator*<OtherConst>& x, const *sentinel*& y); template<bool OtherConst>requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<*zentinel*<Const>, *ziperator*<OtherConst>>friend constexpr range_difference_t<*maybe-const*<OtherConst, *InnerView*>>operator-(const *sentinel*& x, const *iterator*<OtherConst>& y); };}
[🔗](#lib:zip_transform_view::sentinel,constructor)
`constexpr explicit sentinel(zentinel<Const> inner);
`
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12487)
*Effects*: Initializes *inner_* with inner[.](#1.sentence-1)
[🔗](#lib:zip_transform_view::sentinel,constructor_)
`constexpr sentinel(sentinel<!Const> i)
requires Const && [convertible_to](concept.convertible#concept:convertible_to "18.4.4 Concept convertible_­to [concept.convertible]")<zentinel<false>, zentinel<Const>>;
`
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12499)
*Effects*: Initializes *inner_* with std​::​move(i.*inner_*)[.](#2.sentence-1)
[🔗](#lib:operator==,zip_transform_view::sentinel)
`template<bool OtherConst>
requires [sentinel_for](iterator.concept.sentinel#concept:sentinel_for "24.3.4.7 Concept sentinel_­for [iterator.concept.sentinel]")<zentinel<Const>, ziperator<OtherConst>>
friend constexpr bool operator==(const iterator<OtherConst>& x, const sentinel& y);
`
[3](#3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12512)
*Effects*: Equivalent to: return x.*inner_* == y.*inner_*;
[🔗](#lib:operator-,zip_transform_view::sentinel)
`template<bool OtherConst>
requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<zentinel<Const>, ziperator<OtherConst>>
friend constexpr range_difference_t<maybe-const<OtherConst, InnerView>>
operator-(const iterator<OtherConst>& x, const sentinel& y);
template<bool OtherConst>
requires [sized_sentinel_for](iterator.concept.sizedsentinel#concept:sized_sentinel_for "24.3.4.8 Concept sized_­sentinel_­for [iterator.concept.sizedsentinel]")<zentinel<Const>, ziperator<OtherConst>>
friend constexpr range_difference_t<maybe-const<OtherConst, InnerView>>
operator-(const sentinel& x, const iterator<OtherConst>& y);
`
[4](#4)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12530)
*Effects*: Equivalent to: return x.*inner_* - y.*inner_*;

24
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[range.zip.transform.view]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.transform.view)
### 25.7.26 Zip transform view [[range.zip.transform]](range.zip.transform#view)
#### 25.7.26.2 Class template zip_transform_view [range.zip.transform.view]
[🔗](#lib:zip_transform_view)
namespace std::ranges {template<[move_constructible](concept.moveconstructible#concept:move_constructible "18.4.13 Concept move_­constructible [concept.moveconstructible]") F, [input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0) && is_object_v<F> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<F&, range_reference_t<Views>...> &&[*can-reference*](iterator.synopsis#concept:can-reference "24.2 Header <iterator>&nbsp;synopsis [iterator.synopsis]")<invoke_result_t<F&, range_reference_t<Views>...>>class zip_transform_view : public view_interface<zip_transform_view<F, Views...>> {*movable-box*<F> *fun_*; // *exposition only* zip_view<Views...> *zip_*; // *exposition only*using *InnerView* = zip_view<Views...>; // *exposition only*template<bool Const>using *ziperator* = iterator_t<*maybe-const*<Const, *InnerView*>>; // *exposition only*template<bool Const>using *zentinel* = sentinel_t<*maybe-const*<Const, *InnerView*>>; // *exposition only*// [[range.zip.transform.iterator]](range.zip.transform.iterator "25.7.26.3 Class template zip_­transform_­view​::​iterator"), class template zip_transform_view​::​*iterator*template<bool> class *iterator*; // *exposition only*// [[range.zip.transform.sentinel]](range.zip.transform.sentinel "25.7.26.4 Class template zip_­transform_­view​::​sentinel"), class template zip_transform_view​::​*sentinel*template<bool> class *sentinel*; // *exposition only*public: zip_transform_view() = default; constexpr explicit zip_transform_view(F fun, Views... views); constexpr auto begin() { return *iterator*<false>(*this, *zip_*.begin()); }constexpr auto begin() constrequires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const *InnerView*> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<const F&, range_reference_t<const Views>...> {return *iterator*<true>(*this, *zip_*.begin()); }constexpr auto end() {if constexpr ([common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<*InnerView*>) {return *iterator*<false>(*this, *zip_*.end()); } else {return *sentinel*<false>(*zip_*.end()); }}constexpr auto end() constrequires [range](range.range#concept:range "25.4.2 Ranges [range.range]")<const *InnerView*> &&[regular_invocable](concept.regularinvocable#concept:regular_invocable "18.7.3 Concept regular_­invocable [concept.regularinvocable]")<const F&, range_reference_t<const Views>...> {if constexpr ([common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<const *InnerView*>) {return *iterator*<true>(*this, *zip_*.end()); } else {return *sentinel*<true>(*zip_*.end()); }}constexpr auto size() requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<*InnerView*> {return *zip_*.size(); }constexpr auto size() const requires [sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const *InnerView*> {return *zip_*.size(); }}; template<class F, class... Rs> zip_transform_view(F, Rs&&...) -> zip_transform_view<F, views::all_t<Rs>...>;}
[🔗](#lib:zip_transform_view,constructor)
`constexpr explicit zip_transform_view(F fun, Views... views);
`
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L12112)
*Effects*: Initializes *fun_* with std​::​move(fun) and*zip_* with std​::​move(views)...[.](#1.sentence-1)

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[range.zip.view]
# 25 Ranges library [[ranges]](./#ranges)
## 25.7 Range adaptors [[range.adaptors]](range.adaptors#range.zip.view)
### 25.7.25 Zip view [[range.zip]](range.zip#view)
#### 25.7.25.2 Class template zip_view [range.zip.view]
[🔗](#lib:zip_view)
namespace std::ranges {template<class... Rs>concept [*zip-is-common*](#concept:zip-is-common "25.7.25.2 Class template zip_­view [range.zip.view]") = // *exposition only*(sizeof...(Rs) == 1 && ([common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<Rs> && ...)) ||(!([bidirectional_range](range.refinements#concept:bidirectional_range "25.4.6 Other range refinements [range.refinements]")<Rs> && ...) && ([common_range](range.refinements#concept:common_range "25.4.6 Other range refinements [range.refinements]")<Rs> && ...)) ||(([random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Rs> && ...) && ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<Rs> && ...)); template<[input_range](range.refinements#concept:input_range "25.4.6 Other range refinements [range.refinements]")... Views>requires ([view](range.view#concept:view "25.4.5 Views [range.view]")<Views> && ...) && (sizeof...(Views) > 0)class zip_view : public view_interface<zip_view<Views...>> { tuple<Views...> *views_*; // *exposition only*// [[range.zip.iterator]](range.zip.iterator "25.7.25.3 Class template zip_­view​::​iterator"), class template zip_view​::​*iterator*template<bool> class *iterator*; // *exposition only*// [[range.zip.sentinel]](range.zip.sentinel "25.7.25.4 Class template zip_­view​::​sentinel"), class template zip_view​::​*sentinel*template<bool> class *sentinel*; // *exposition only*public: zip_view() = default; constexpr explicit zip_view(Views... views); constexpr auto begin() requires (!([*simple-view*](range.utility.helpers#concept:simple-view "25.5.2 Helper concepts [range.utility.helpers]")<Views> && ...)) {return *iterator*<false>(*tuple-transform*(ranges::begin, *views_*)); }constexpr auto begin() const requires ([range](range.range#concept:range "25.4.2 Ranges [range.range]")<const Views> && ...) {return *iterator*<true>(*tuple-transform*(ranges::begin, *views_*)); }constexpr auto end() requires (!([*simple-view*](range.utility.helpers#concept:simple-view "25.5.2 Helper concepts [range.utility.helpers]")<Views> && ...)) {if constexpr (![*zip-is-common*](#concept:zip-is-common "25.7.25.2 Class template zip_­view [range.zip.view]")<Views...>) {return *sentinel*<false>(*tuple-transform*(ranges::end, *views_*)); } else if constexpr (([random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<Views> && ...)) {return begin() + iter_difference_t<*iterator*<false>>(size()); } else {return *iterator*<false>(*tuple-transform*(ranges::end, *views_*)); }}constexpr auto end() const requires ([range](range.range#concept:range "25.4.2 Ranges [range.range]")<const Views> && ...) {if constexpr (![*zip-is-common*](#concept:zip-is-common "25.7.25.2 Class template zip_­view [range.zip.view]")<const Views...>) {return *sentinel*<true>(*tuple-transform*(ranges::end, *views_*)); } else if constexpr (([random_access_range](range.refinements#concept:random_access_range "25.4.6 Other range refinements [range.refinements]")<const Views> && ...)) {return begin() + iter_difference_t<*iterator*<true>>(size()); } else {return *iterator*<true>(*tuple-transform*(ranges::end, *views_*)); }}constexpr auto size() requires ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<Views> && ...); constexpr auto size() const requires ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const Views> && ...); }; template<class... Rs> zip_view(Rs&&...) -> zip_view<views::all_t<Rs>...>;}
[1](#1)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11439)
Two zip_view objects have the same underlying sequence if and only if
the corresponding elements of *views_* are equal ([[concepts.equality]](concepts.equality "18.2 Equality preservation"))
and have the same underlying sequence[.](#1.sentence-1)
[*Note [1](#note-1)*:
In particular, comparison of iterators obtained from zip_view objects
that do not have the same underlying sequence
is not required to produce meaningful results ([[iterator.concept.forward]](iterator.concept.forward "24.3.4.11 Concept forward_­iterator"))[.](#1.sentence-2)
— *end note*]
[🔗](#lib:zip_view,constructor)
`constexpr explicit zip_view(Views... views);
`
[2](#2)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11455)
*Effects*: Initializes *views_* with std​::​move(views)...[.](#2.sentence-1)
[🔗](#lib:size,zip_view)
`constexpr auto size() requires ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<Views> && ...);
constexpr auto size() const requires ([sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<const Views> && ...);
`
[3](#3)
[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/ranges.tex#L11467)
*Effects*: Equivalent to:return apply([](auto... sizes) {using CT = *make-unsigned-like-t*<common_type_t<decltype(sizes)...>>; return ranges::min({CT(sizes)...});}, *tuple-transform*(ranges::size, *views_*));