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std::ranges::zip_transform_view<F,Views...>::size

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Ranges library
Range access
Range conversions
(C++23)

Range primitives



Dangling iterator handling
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(until C++23)(C++23)


 
 
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();.

Contents

[edit] Parameters

(none)

[edit] Return value

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

[edit] Example

#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 << ' ';
    std::cout << '\n';
 
    [[maybe_unused]] auto v2 = std::views::zip_transform(std::plus{}, x, z);
//  auto sz = v2.size(); // Error: z doesn't have size(), so neither does v2
    static_assert(not std::ranges::sized_range<decltype(z)>);
}

Output:

11 22 33

[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]