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std::make_optional

STD：使[医]任选

Defined in header ​​
template< class T > constexpr std::optional<std::decay_t<T>> make_optional( T&& value (1)(since C++17)
template< class T, class... Args > constexpr std::optional<T> make_optional( Args&&... args (2)(since C++17)
template< class T, class U, class... Args > constexpr std::optional<T> make_optional( std::initializer_list<U> il, Args&&... args (3)(since C++17)

1%29从value.有效地打电话std::optional<std::decay_t<T>>(std::forward<T>(value))

2%29从args...相当于returnstd::optional<T>(std::in_place,std::forward<Args>(args)......

3%29从il和args...相当于returnstd::optional<T>(std::in_place, il,std::forward<Args>(args)......

参数

value-the value to construct optional object with
il, args-arguments to be passed to the constructor of T.

返回值

构造的可选对象。

例外

的构造函数引发的任何异常。T...

注记

T由于有保证的复制省略，不必为过载%282-3%29而移动。

另见

(constructor)constructs the optional object (public member function)

 © cppreference.com

在CreativeCommonsAttribution下授权-ShareAlike未移植许可v3.0。

http：//en.cppreference.com/w/cpp/实用程序/可选/make[医]任选

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