lib/variantpoly2.cpp

The following code example is taken from the book
C++17 - The Complete Guide by Nicolai M. Josuttis, Leanpub, 2017
The code is licensed under a Creative Commons Attribution 4.0 International License.

---

// raw code

#include <iostream>
#include <string>
#include <variant>
#include <vector>
#include <type_traits>

int main()
{
  using Var = std::variant<int, double, std::string>;

  std::vector<Var> values {42, 0.19, "hello world", 0.815};

  for (const Var& val : values) {
    std::visit([] (const auto& v) {
                 if constexpr(std::is_same_v<decltype(v),
                              const std::string&>) {
                   std::cout << '"' << v << "\" ";
                 }
                 else {
                   std::cout << v << ' ';
                 }
               },
               val);
  }
}