ranges/transformview.cpp

The following code example is taken from the book
C++20 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2021
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <iostream>
#include <string>
#include <vector>
#include <ranges>
#include <cmath>   // for std::sqrt()

void print(std::ranges::input_range auto&& coll)
{
  for (const auto& elem : coll) {
    std::cout << elem << ' ';
  }
  std::cout << '\n';
}

int main()
{
  std::vector coll{1, 2, 3, 4, 1, 2, 3, 4, 1};

  print(coll);                                       // 1 2 3 4 1
  auto sqrt = [] (auto v) { return std::sqrt(v); };
  print(std::ranges::transform_view{coll, sqrt});    // 1 1.41421 1.73205 2 1
  print(coll | std::views::transform(sqrt));         // 1 1.41421 1.73205 2 1
}