core/lambdarec.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>

int main()
{
  auto fib = [](this auto self, int n) {
               if (n <= 1) return 1;  // we start with 1 and 1
               return self(n - 1) + self(n - 2);
             };

  for (int n : {8, 12, 16}) {
    std::println("the {:2}-th Fibonacci number is {:4}", n, fib(n));
  }
}