Pipelines

Questions 1 to 5 of 6

1. 1. What does this print? ``cpp std::vector<int> v = {1, 2, 3, 4, 5, 6}; auto r = v | std::views::filter([](int x) { return x % 3 == 0; }) | std::views::transform([](int x) { return x * 10; }); std::cout << std::accumulate(r.begin(), r.end(), 0) << ' ' << std::ranges::distance(r); ``

   30 290 290 3120 2
2. 2. What does this print? ``cpp std::vector<double> v = {2.5, 2.5, 2.5}; int total = std::accumulate(v.begin(), v.end(), 0); std::cout << total; ``

   7467.5
3. 3. What does this print? ``cpp std::vector<std::string> w = {"tea", "kettle", "cup", "saucer"}; auto p = w | std::views::filter([](const std::string& s) { return s.size() >= 4; }) | std::views::transform([](const std::string& s) { return s.front(); }); for (char c : p) std::cout << c; std::cout << std::ranges::distance(p); ``

   ks3kettlesaucer2tcs4ks2
4. 4. Put these steps in the order that a pipeline totals the even amounts in a vector.

   Use the arrows to put the steps in order.

   1. 1.Pipe the vector into a filter that keeps the even amounts↑↓
   2. 2.Pipe the kept amounts into a transform that doubles each one↑↓
   3. 3.Pass the view to std::accumulate to get the sum↑↓
   4. 4.Start with the vector of amounts↑↓
5. 5. Why can std::ranges::sort not sort a filter view directly?

   Sorting needs to jump to any position, and a filter view can only step forward or backward one item at a timeA filter view stores its items in a fixed order that the sort cannot changestd::ranges::sort works only on std::vector, and a view is not a vectorA filter view is read-only, and sort is not allowed on read-only data