Modern C++ Programming Cookbook

How to do it...

Use the following operations to work with std::variant:

• To modify the stored value, use member functions emplace() or swap():

        struct foo        {          int value;          explicit foo(int const i) : value(i) {}        };        std::variant<int, std::string, foo> v = 42; // holds int        v.emplace<foo>(42);                         // holds foo

• To read the stored values, use non-member functions std::get or std::get_if:

        std::variant<int, double, std::string> v = 42;        auto i1 = std::get<int>(v);        auto i2 = std::get<0>(v);        try        {          auto f = std::get<double>(v);        }        catch (std::bad_variant_access const & e)        {          std::cout << e.what() << std::endl; // Unexpected index        }

• To store a value, use the constructor or assign a value directly to a variant object:

 std::variant<int, double, std::string> ...