std::ranges::cartesian_product_view<First, Vs...>::size

Returns the number of elements. The return type is an implementation-defined /*unsigned-integer-like*/ type U

Let bases_ be the underlying tuple of views, and prod be the product of the sizes of all the ranges in bases_

return [&]<std::size_t... Is>(std::index_sequence<Is...>)
{
    auto prod = static_cast<U>(1);
    prod = (static_cast<U>(ranges::size(std::get<Is>(bases_))) * ...);
    return prod;
}
(std::make_index_sequence<1U + sizeof...(Vs)>{});

Parameters

(none)

Return value

The number of elements, that is, the product of the sizes of all the underlying ranges.

Notes

The return type is the smallest /*unsigned-integer-like*/

Example

#include <ranges>
 
int main()
{
    constexpr static auto w = {1};
    constexpr static auto x = {2, 3};
    constexpr static auto y = {4, 5, 6};
    constexpr static auto z = {7, 8, 9, 10, 11, 12, 13};
    constexpr auto v = std::ranges::cartesian_product_view(w, x, y, z);
    static_assert(v.size() == w.size() * x.size() * y.size() * z.size() and v.size() == 42);
}

See also