如何uninitialize std :: experimental ::可選

Question

如何uninitialize 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; 
    } 

我該如何擊中else分支？

Answer 1

name = std::experimental::nullopt; 

link

的std ::實驗:: nullopt是類型爲std ::實驗:: nullopt_t是，用於指示可選類型與未初始化狀態的一個常數。