std::ranges::slide_view::size - cppreference.com (original) (raw)

Returns the number of elements.

Let _[base](../slide%5Fview.html#base "cpp/ranges/slide view")_ and _[n](../slide%5Fview.html#n "cpp/ranges/slide view")_ be the underlying view and “window size” respectively. Equivalent to

auto sz = ranges::distance(base_) - n_ + 1; if (sz < 0) sz = 0; return /to-unsigned-like/(sz);

[edit] Return value

The number of elements. Equals to ​0​, if the number of elements (ranges::size(_[base](../slide%5Fview.html#base "cpp/ranges/slide view")_)) in underlying view _[base](../slide%5Fview.html#base "cpp/ranges/slide view")_ is less than “window size” _[n](../slide%5Fview.html#n "cpp/ranges/slide view")_.

[edit] Example

#include #include #include #include   int main() { constexpr static auto v = {1, 2, 3, 4, 5, 6};   constexpr int width1{4}; constexpr auto view1{std::views::slide(v, width1)}; static_assert(view1.size() == 3); static_assert(view1.size() == (v.size() - width1 + 1));   constexpr int width2{8}; constexpr auto view2{std::views::slide(v, width2)}; // window is too wide, so view2 has no elements: static_assert(view2.size() == 0);   std::forward_list forward_list = v; const auto view3{std::views::slide(forward_list, width1)}; // auto x = view3.size(); // error: sized_range constraint is not satisfied   std::list list = v; const auto view4{std::views::slide(list, width1)}; std::cout << view4.size() << '\n'; // prints 3 }

Output:

[edit] 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] |