ranges/filtermod3.cpp

The following code example is taken from the book
C++23 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2026
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <print>
#include <vector>
#include <ranges>

int main()
{
  std::vector coll{1, 4, 7, 10};

  // define view for even elements (not applied to coll):
  auto even = [](int i){ return i%2 == 0;};
  auto vEven = std::views::filter(even);

  // add just some debug output:
  std::println("even: {}", coll | vEven);   // apply the view to coll

  // modify underlying range:
  coll[0] = 0;

  // print collection and view:
  std::println("coll: {}", coll);
  std::println("even: {}", coll | vEven);   // apply the view to coll
}