std::ranges::views::zip, std::ranges::zip_view

 

C++

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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::zip_view

Member functions

zip_view::zip_view (C++23)

zip_view::begin (C++23)

zip_view::end (C++23)

zip_view::size (C++23)

Deduction guides

Iterator

zip_view::iterator::iterator (C++23)

zip_view::iterator::operator* (C++23)

zip_view::iterator::operator[] (C++23)

zip_view::iterator::operator++ zip_view::iterator::operator++(int) zip_view::iterator::operator-- zip_view::iterator::operator--(int) zip_view::iterator::operator+= zip_view::iterator::operator-= (C++23)(C++23)(C++23)(C++23)(C++23)(C++23)

operator==(zip_view::iterator) operator<(zip_view::iterator) operator>(zip_view::iterator) operator<=(zip_view::iterator) operator>=(zip_view::iterator) operator<=>(zip_view::iterator) (C++23)(C++23)(C++23)(C++23)(C++23)(C++23)

operator+(zip_view::iterator) operator-(zip_view::iterator) (C++23)(C++23)

iter_move(zip_view::iterator) (C++23)

iter_swap(zip_view::iterator) (C++23)

Sentinel

zip_view::sentinel::sentinel (C++23)

operator==(zip_view::sentinel) (C++23)

operator-(zip_view::sentinel) (C++23)

 

Defined in header <ranges>
template< ranges::input_range... Views >     requires (ranges::view<Views> && ...) && (sizeof...(Views) > 0) class zip_view : public ranges::view_interface<zip_view<Views...>>	(1)	(since C++23)
namespace views {     inline constexpr /*unspecified*/ zip = /*unspecified*/; }	(2)	(since C++23)
Call signature
template< ranges::viewable_range... Rs >     requires /* see below */ constexpr auto zip( Rs&&... rs );		(since C++23)

1) zip_view is a range adaptor that takes one or more views, and produces a view whose ith element is a tuple-like value consisting of the ith elements of all views. The size of produced view is the minimum of sizes of all adapted views.

2) views::zip is a customization point object.

When calling with no argument, views::zip() is expression-equivalent to auto(views::empty<std::tuple<>>).

Otherwise, views::zip(rs...) is expression-equivalent to ranges::zip_view<views::all_t<decltype((rs))>...>(rs...).

zip_view always models input_range, and models forward_range, bidirectional_range, random_access_range, or sized_range if all adapted view types model the corresponding concept.

zip_view models common_range if

• sizeof...(Views) is equal to 1, and the only adapted view type models common_range, or
• at least one adapted view type does not model bidirectional_range, and every adapted view type models common_range, or
• every adapted view type models both random_access_range and sized_range.

Customization point objects

The name views::zip denotes a customization point object, which is a const function object of a literal semiregular class type. For exposition purposes, the cv-unqualified version of its type is denoted as __zip_fn.

All instances of __zip_fn are equal. The effects of invoking different instances of type __zip_fn on the same arguments are equivalent, regardless of whether the expression denoting the instance is an lvalue or rvalue, and is const-qualified or not (however, a volatile-qualified instance is not required to be invocable). Thus, views::zip can be copied freely and its copies can be used interchangeably.

Given a set of types Args..., if std::declval<Args>()... meet the requirements for arguments to views::zip above, __zip_fn models

• std::invocable<__zip_fn, Args...>,
• std::invocable<const __zip_fn, Args...>,
• std::invocable<__zip_fn&, Args...>, and
• std::invocable<const __zip_fn&, Args...>.
  

Otherwise, no function call operator of __zip_fn participates in overload resolution.

Expression-equivalent

Expression e is expression-equivalent to expression f, if

• e and f have the same effects, and
• either both are constant subexpressions or else neither is a constant subexpression, and
• either both are potentially-throwing or else neither is potentially-throwing (i.e. noexcept(e) == noexcept(f)).

Data members

Typical implementations of zip_view hold only one non-static data member: a std::tuple<Views...> holding all adapted view objects.

For the purpose of exposition, the view objects in that std::tuple are shown as vs_... here.

Member functions

(constructor) (C++23)	constructs a zip_view (public member function)
begin (C++23)	returns an iterator to the beginning (public member function)
end (C++23)	returns an iterator or a sentinel to the end (public member function)
size (C++23)	returns the number of elements. Provided only if each underlying (adapted) range satisfies sized_range. (public member function)
Inherited from std::ranges::view_interface
empty (C++20)	Returns whether the derived view is empty. Provided if it satisfies sized_range or forward_range. (public member function of std::ranges::view_interface<D>)
operator bool (C++20)	Returns whether the derived view is not empty. Provided if ranges::empty is applicable to it. (public member function of std::ranges::view_interface<D>)
front (C++20)	Returns the first element in the derived view. Provided if it satisfies forward_range. (public member function of std::ranges::view_interface<D>)
back (C++20)	Returns the last element in the derived view. Provided if it satisfies bidirectional_range and common_range. (public member function of std::ranges::view_interface<D>)
operator[] (C++20)	Returns the nth element in the derived view. Provided if it satisfies random_access_range. (public member function of std::ranges::view_interface<D>)

Nested classes

iterator (C++23)	the iterator type (exposition-only member class template)
sentinel (C++23)	the sentinel type used when zip_view is not a common_range (exposition-only member class template)

Notes

Feature-test macro:

__cpp_lib_ranges_zip

Example

Can be checked online on Compiler Explorer site.

Run this code

#include <list>
#include <array>
#include <tuple>
#include <ranges>
#include <vector>
#include <string>
#include <iostream>
 
void print(auto const rem, auto const& range) {
   for (std::cout << rem; auto const& elem : range)
     std::cout << elem << ' ';
   std::cout << '\n';
}
 
int main() {
    auto x = std::vector{1, 2, 3, 4};
    auto y = std::list<std::string>{"α", "β", "γ", "δ", "ε"};
    auto z = std::array{'A', 'B', 'C', 'D', 'E', 'F'};
 
    print("Source views:", "");
    print("x: ", x);
    print("y: ", y);
    print("z: ", z);
 
    print("\nzip(x,y,z):", "");
    for (std::tuple<int&, std::string&, char&> elem : std::views::zip(x, y, z)) {
        std::cout << std::get<0>(elem) << ' '
                  << std::get<1>(elem) << ' '
                  << std::get<2>(elem) << '\n';
 
        std::get<char&>(elem) += ('a' - 'A'); // modifies the element of z
    }
 
    print("\nAfter modification, z: ", z);
}

Output:

Source views:
x: 1 2 3 4
y: α β γ δ ε
z: A B C D E F
 
zip(x,y,z):
1 α A
2 β B
3 γ C
4 δ D
 
After modification, z: a b c d E F

See also

ranges::zip_transform_viewviews::zip_transform (C++23)

a view consisting of tuples of results of application of a transformation function to corresponding elements of the adapted views (class template) (customization point object)