Range Adaptors views::filter transform take
Compose lazy range pipelines with views::filter, views::transform, and views::take.
Range Adaptors views::filter transform take is a free C++ Academy lesson on CoddyKit. This is lesson 4 of 4. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the C++ Academy learning path, and your progress syncs across the web and the CoddyKit app. The C++ Academy course includes 4 lessons in total.
The Three Core Adaptors
The most common range adaptors:
std::views::filter— keep elements matching a predicatestd::views::transform— apply a function to eachstd::views::take— keep the first n
views::filter
Lazy filter — returns a view that yields only matching elements.
auto evens = v | std::views::filter([](int x) { return x % 2 == 0; });
for (int x : evens) std::cout << x << " ";views::transform
Lazy map — applies a function to each element as it is iterated.
auto squared = v | std::views::transform([](int x) { return x * x; });
for (int x : squared) std::cout << x << " ";views::take
Limit a range to the first n elements. Combines with infinite ranges nicely.
auto first5 = v | std::views::take(5);views::drop
Skip the first n elements; iterate the rest.
auto rest = v | std::views::drop(3); // skip first 3views::reverse
Iterate a range in reverse without copying.
auto reversed = v | std::views::reverse;
for (int x : reversed) std::cout << x << " ";Chaining Adaptors
Compose adaptors with the pipe operator. The order matters — each step is applied to the result of the previous.
auto result = v
| std::views::filter([](int x) { return x > 0; })
| std::views::transform([](int x) { return x * 2; })
| std::views::take(3);views::iota
Generate a lazy sequence of integers. Combine with take to bound infinite ranges.
for (int x : std::views::iota(1) | std::views::take(5)) {
std::cout << x << " ";
}
// 1 2 3 4 5Materializing a View
A view is not a container — iterate it or copy elements into a container if needed. C++23 adds std::ranges::to.
std::vector<int> result;
for (int x : squared) result.push_back(x);
// C++23 (when available): auto result = squared | std::ranges::to<std::vector>();Common-Range View
Some algorithms require begin and end to share a type. views::common adapts a view to satisfy that requirement.
Avoid Side Effects in Predicates
Filter and transform may be called multiple times per element. Predicates with side effects (printing, counters) lead to surprising results.
Performance Notes
Modern compilers inline lazy view chains very well. Performance often matches a hand-written single loop — sometimes better, by avoiding intermediate containers.
Quick Check
Which adaptor would you use to keep only elements satisfying a condition?
Recap
Range adaptors (filter, transform, take, drop, reverse, iota) compose with | into lazy pipelines. They avoid intermediate containers and compile to efficient code.
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Is the “Range Adaptors views::filter transform take” lesson free?
Yes — any 3 lessons of the C++ Academy learning path, including “Range Adaptors views::filter transform take”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The C++ Academy course includes 4 lessons in total.
What will I learn in “Range Adaptors views::filter transform take”?
Compose lazy range pipelines with views::filter, views::transform, and views::take. You practise C++ Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
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All lessons in this course
- Iterator Categories input forward bidirectional random
- Common Iterator Patterns begin end advance
- C++20 Ranges Library Introduction
- Range Adaptors views::filter transform take