NAME¶

std::ranges::adjacent_view::size - std::ranges::adjacent_view::size

Synopsis¶

constexpr auto size() requires ranges::sized_range<V>; (since C++23)
constexpr auto size() const requires ranges::sized_range<const V>; (since C++23)

Returns the number of elements.

Let base_ be the underlying view. Equivalent to:

using SizeType = decltype(ranges::size(base_));
using CommonType = ranges::common_type_t<SizeType, std::size_t>;
auto size = static_cast<CommonType>(ranges::size(base_));
size -= std::min<CommonType>(size, N - 1);
return static_cast<SizeType>(size);

Parameters¶

(none)

Return value¶

The number of elements, may be 0 if ranges::size(base_) is less than N.

Example¶

// Run this code

#include <ranges>

int main()
{
constexpr static auto v = {1, 2, 3, 4, 5, 6};

constexpr int width1 {4};
constexpr auto view1 {std::views::adjacent<width1>(v)};
static_assert(view1.size() == 3);
static_assert(view1.size() == (v.size() - width1 + 1));

constexpr int width2 {8};
constexpr auto view2 {std::views::adjacent<width2>(v)};
// window is too wide, so view2 has no elements:
static_assert(view2.size() == 0);
}

See also¶

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