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

Returns the number of elements. Equivalent to return ranges::size(base_);, where base_ is the underlying view.

[edit] Parameters

(none)

[edit] Return value

The number of elements.

[edit] Example

#include #include #include #include   int main() { constexpr static auto v1 = {1, 2, 3, 4, 5}; constexpr auto ev1{v1 | std::views::enumerate}; static_assert(ev1.size() == 5); static_assert(std::ranges::sized_range<decltype(v1)>);   auto v2 = std::forward_list{1, 2, 3, 4, 5}; auto ev2 {v2 | std::views::enumerate}; static_assert(not std::ranges::sized_range<decltype(v2)>); // auto size = ev2.size(); // Error: v2 is not a sized range assert(std::ranges::distance(v2) == 5); // OK, distance does not require sized // range, but has O(N) complexity here }

[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] |