如何取消初始化std :: experimental :: optional

Question

如何取消初始化std :: experimental :: optional？

  std::experimental::optional<std::string> name;

  name = std::string("hello"); //how to uninitialize name?

  if(name)
  {
    std::cout << "name is set" << std::endl;
  }
  else
  {
    std::cout << "name is not set" << std::endl;
  }

我怎么打else分支？

Answer 1

name = std::experimental::nullopt; 

鏈接

std :: experimental :: nullopt是類型為std :: experimental :: nullopt_t的常量，用於指示具有未初始化狀態的可選類型。