constexpr auto size()
requires (ranges::sized_range<Views> && ...);
| (1) | (since C++23) |
constexpr auto size() const
requires (ranges::sized_range<const Views> && ...);
| (2) | (since C++23) |
Returns the number of elements in the zip_view. Provided only if each underlying (adapted) range satisfies sized_range.
Equivalent to:
return std::apply(
[](auto... sizes) {
using CT = /*make-unsigned-like-t*/<std::common_type_t<decltype(sizes)...>>;
return ranges::min({CT(sizes)...});
},
/*tuple-transform*/(ranges::size, views_)
);(none).
The number of elements, which is the minimum size among all sizes of adapted views.
Can be tested on Compiler Explorer site.
#include <algorithm>
#include <cassert>
#include <deque>
#include <forward_list>
#include <ranges>
#include <vector>
int main()
{
auto x = std::vector{1, 2, 3, 4, 5};
auto y = std::deque{'a', 'b', 'c'};
auto z = std::forward_list{1., 2.};
auto v1 = std::views::zip(x, y);
assert(v1.size() == std::min(x.size(), y.size()));
assert(v1.size() == 3);
[[maybe_unused]] auto v2 = std::views::zip(x, z);
// auto sz = v2.size(); // Error, v2 does not have size():
static_assert(not std::ranges::sized_range<decltype(z)>);
}|
(C++20) | returns an integer equal to the size of a range (customization point object) |
|
(C++20) | returns a signed integer equal to the size of a range (customization point object) |
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https://en.cppreference.com/w/cpp/ranges/zip_view/size