# std::expected<T,E>::emplace

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< cpp‎ | utility‎ | expected

T is not cv void |  |
template< class... Args > constexpr T& emplace( Args&&... args ) noexcept; | (1) | (since C++23)
template< class U, class... Args > constexpr T& emplace( std::initializer_list<U>& il, Args&&... args ) noexcept; | (2) | (since C++23)
T is cv void |  |
constexpr void emplace() noexcept; | (3) | (since C++23)

Constructs an expected value in-place. After the call, `has_value()` returns true.

1) Destroys the contained value, then initializes the expected value contained in *this as if by direct-initializing an object of type `T` from the arguments std::forward<Args>(args).... This overload participates in overload resolution only if std::is_nothrow_constructible_v<T, Args...> is true.
2) Destroys the contained value, then initializes the expected value contained in *this as if by direct-initializing an object of type `T` from the arguments il, std::forward<Args>(args).... This overload participates in overload resolution only if std::is_nothrow_constructible_v<T, std::initializer_list<U>&, Args...> is true.
3) If *this contains an unexpected value, destroys that value.

### Parameters

args... | - | the arguments to pass to the constructor
il | - | the initializer list to pass to the constructor

### Return value

A reference to the new contained value.

### Exceptions

`noexcept` specification:
noexcept

### Notes

If the construction of `T` is potentially-throwing, this function is not defined. In this case, it is the responsibility of the user to create a temporary and move or copy it.

### Example

| This section is incomplete Reason: no example

### See also

operator= (C++23) | assigns contents (public member function)

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