std::make_optional - cppreference.com (original) (raw)
| 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) |
- Creates an optional object constructed in-place from args.... Equivalent to return std::optional<T>(std::in_place, std::forward<Args>(args)...);.
This overload participates in overload resolution only if std::is_constructible_v<T, Args...> is true.
[edit] Parameters
| value | - | the value to construct optional object with |
|---|---|---|
| il, args | - | arguments to be passed to the constructor of T |
[edit] Return value
The constructed optional object.
[edit] Exceptions
Throws any exception thrown by the constructor of T.
[edit] Notes
T need not be movable for overloads (2,3) due to guaranteed copy elision.
[edit] Example
Possible output:
op1: a,b,c, op2: 2,2,2,2,2, op3: "hello world" str: ""