constexpr auto size()
    requires ranges::sized_range</*InnerView*/>;
(1) (since C++23)
constexpr auto size() const
    requires ranges::sized_range<const /*InnerView*/>
(2) (since C++23)

Returns the number of elements in the zip_transform_view. Provided only if each underlying (adapted) range satisfies sized_range.

1,2) Equivalent to: return zip_.size();.



Return value

The number of elements, which is the minimum size among all sizes of adapted views.


#include <algorithm>
#include <cassert>
#include <deque>
#include <forward_list>
#include <functional>
#include <iostream>
#include <ranges>
#include <vector>
int main()
    auto x = std::vector{1, 2, 3, 4, 5};
    auto y = std::deque<short>{10, 20, 30};
    auto z = std::forward_list{100., 200.};
    auto v1 = std::views::zip_transform(std::plus, x, y);
    assert(v1.size() == std::min(x.size(), y.size()));
    assert(v1.size() == 3);
    for (int i : v1) std::cout << i << '\n';
    [[maybe_unused]] auto v2 = std::views::zip_transform(std::plus, x, z);
//  auto sz = v2.size(); // Error, v2 does not have size():
    static_assert(not std::ranges::sized_range<decltype(z)>);


11 22 33

See also

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

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