25 Ranges library [ranges]

25.7 Range adaptors [range.adaptors]

25.7.33 Cartesian product view [range.cartesian]

25.7.33.1 Overview [range.cartesian.overview]

1
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cartesian_product_view takes any non-zero number of ranges n and produces a view of tuples calculated by the n-ary cartesian product of the provided ranges.
2
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The name views​::​cartesian_product denotes a customization point object ([customization.point.object]).
Given a pack of subexpressions Es, the expression views​::​cartesian_product(Es...) is expression-equivalent to
  • (2.1)
    views​::​single(tuple()) if Es is an empty pack,
  • (2.2)
    otherwise, cartesian_product_view<views​::​all_t<decltype((Es))>...>(Es...).
3
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[Example 1: vector<int> v { 0, 1, 2 }; for (auto&& [a, b, c] : views::cartesian_product(v, v, v)) { cout << a << ' ' << b << ' ' << c << '\n'; } // The above prints // 0 0 0 // 0 0 1 // 0 0 2 // 0 1 0 // 0 1 1 // ... — end example]