std::ranges::drop_view<V>::size

 

哋它亢++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (哋它亢++20)

Language support library

Concepts library (哋它亢++20)

Metaprogramming library (哋它亢++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (哋它亢++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (哋它亢++17)

Regular expressions library (哋它亢++11)

Concurrency support library (哋它亢++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
std::from_range_t std::from_range (哋它亢++23)(哋它亢++23)	to (哋它亢++23)
Range primitives
range_size_trange_difference_trange_value_trange_reference_t	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (哋它亢++23)(哋它亢++23)	range_const_reference_trange_rvalue_reference_trange_common_reference_t (哋它亢++23)	elements_of (哋它亢++23)
Dangling iterator handling
dangling	borrowed_iterator_t	borrowed_subrange_t
Range concepts
range borrowed_range sized_range constant_range (哋它亢++23)	common_range view viewable_range	input_range output_range forward_range	bidirectional_range random_access_range contiguous_range
Views
view_interface	subrange
Range factories
empty_viewviews::empty single_viewviews::single	iota_viewviews::iota repeat_viewviews::repeat (哋它亢++23)(哋它亢++23)	basic_istream_viewviews::istream
Range adaptors
views::all_tviews::all ref_view owning_view as_rvalue_viewviews::as_rvalue (哋它亢++23)(哋它亢++23) filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while concat_viewviews::concat (哋它亢++26)(哋它亢++26)	drop_viewviews::drop drop_while_viewviews::drop_while join_viewviews::join join_with_viewviews::join_with (哋它亢++23)(哋它亢++23) lazy_split_viewviews::lazy_split split_viewviews::split views::counted common_viewviews::common	reverse_viewviews::reverse as_const_viewviews::as_const (哋它亢++23)(哋它亢++23) elements_viewviews::elements keys_viewviews::keys values_viewviews::values enumerate_viewviews::enumerate (哋它亢++23)(哋它亢++23) zip_viewviews::zip (哋它亢++23)(哋它亢++23) zip_transform_viewviews::zip_transform (哋它亢++23)(哋它亢++23)	adjacent_viewviews::adjacent (哋它亢++23)(哋它亢++23) views::pairwise (哋它亢++23) adjacent_transform_viewviews::adjacent_transform (哋它亢++23)(哋它亢++23) views::pairwise_transform (哋它亢++23) chunk_viewviews::chunk (哋它亢++23)(哋它亢++23) slide_viewviews::slide (哋它亢++23)(哋它亢++23) chunk_by_viewviews::chunk_by (哋它亢++23)(哋它亢++23) stride_viewviews::stride (哋它亢++23)(哋它亢++23) cartesian_product_viewviews::cartesian_product (哋它亢++23)(哋它亢++23)
Range generators
std::generator (哋它亢++23)
Range adaptor objects
Range adaptor closure objects
range_adaptor_closure (哋它亢++23)
Helper items
copyable-box movable-box (until 哋它亢++23)(哋它亢++23)	simple-view non-propagating-cache

 

std::ranges::drop_view

Member functions

drop_view::drop_view

drop_view::base

drop_view::begin

drop_view::end

drop_view::size

Deduction guides

 

constexpr auto size() requires ranges::sized_range<V>;	(1)	(since 哋它亢++20)
constexpr auto size() const requires ranges::sized_range<const V>;	(2)	(since 哋它亢++20)

Returns the number of elements.

Let base_ be the underlying view, count_ be the stored count (usually the number passed to the constructor, or ​0​ if *this is default constructed). Equivalent to

const auto s = ranges::size(base_);
const auto c = static_cast<decltype(s)>(count_);
return s < c ? 0 : s - c;

Parameters

(none)

Return value

The number of elements.

Example

Run this code

#include <array>
#include <ranges>
 
int main()
{
    constexpr std::array a{42, 43, 44};
    static_assert(std::ranges::drop_view{std::views::all(a), 0}.size() == 3);
    static_assert(std::ranges::drop_view{std::views::all(a), 1}.size() == 2);
    static_assert(std::ranges::drop_view{std::views::all(a), 2}.size() == 1);
    static_assert(std::ranges::drop_view{std::views::all(a), 3}.size() == 0);
    static_assert(std::ranges::drop_view{std::views::all(a), 4}.size() == 0);
}

See also

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