std::ranges::zip_view<Views...>::size

 

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::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)

 

constexpr auto size()     requires (ranges::sized_range<Views> && ...);	(1)	(since C++23)
constexpr auto size() const     requires (ranges::sized_range<const Views> && ...);	(2)	(since C++23)

Returns the number of elements in the zip_view. Provided only if each underlying (adapted) range satisfies sized_range.

Equivalent to:

return std::apply(
           [](auto... sizes) {
               using CT = /*make-unsigned-like-t*/<std::common_type_t<decltype(sizes)...>>;
               return ranges::min({CT(sizes)...});
           },
           /*tuple-transform*/(ranges::size, views_)
       );

Parameters

(none)

Return value

The number of elements, which is the minimum size among all sizes of adapted views.

Example

Can be tested on Compiler Explorer site.

Run this code

#include <algorithm>
#include <cassert>
#include <deque>
#include <forward_list>
#include <ranges>
#include <vector>
 
int main()
{
    auto x = std::vector{1, 2, 3, 4, 5};
    auto y = std::deque{'a', 'b', 'c'};
    auto z = std::forward_list{1., 2.};
 
    auto v1 = std::views::zip(x, y);
    assert(v1.size() == std::min(x.size(), y.size()));
    assert(v1.size() == 3);
 
    [[maybe_unused]] auto v2 = std::views::zip(x, z);
//  auto sz = v2.size(); // Error, v2 does not have size():
    static_assert(not std::ranges::sized_range<decltype(z)>);
}

See also

ranges::size (C++20)	returns an integer equal to the size of a range (customization point object)
ranges::ssize (C++20)	returns a signed integer equal to the size of a range (customization point object)