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std::ranges::adjacent_transform_view<V,F,N>::size - cppreference.com

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constexpr auto size() requires ranges::sized_range<InnerView>;

 (since C++23)

constexpr auto size() const requires ranges::sized_range<const InnerView>;

 (since C++23)

Returns the number of elements.

Let inner_ be the underlying object of type InnerView (that is the ranges::adjacent_view<V,N>).

1,2) Equivalent to return inner_.size();.

Parameters

(none)

Return value

The number of elements, may be 0 if the size of the underlying view V is less than N.

Example

#include <ranges>

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

    auto f = [](auto...) { return 0; }; // dummy

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

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

See also

returns an integer equal to the size of a range
(customization point object)[edit]
returns a signed integer equal to the size of a range
(customization point object)[edit]