NAME¶

std::ranges::zip_transform_view::size - std::ranges::zip_transform_view::size

Synopsis¶

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

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();.

Parameters¶

(none)

Return value¶

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

Example¶

// Run this code

#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

See also¶

ranges::size returns an integer equal to the size of a range
(C++20) (customization point object)
ranges::ssize returns a signed integer equal to the size of a range
(C++20) (customization point object)