# std::swap(std::optional)

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< cpp‎ | utility‎ | optional

Defined in header `<optional>` |  |
template< class T > void swap( optional<T>& lhs, optional<T>& rhs ) noexcept(/* see below */); |  | (since C++17)

Overloads the std::swap algorithm for std::optional. Exchanges the state of `lhs` with that of `rhs`. Effectively calls lhs.swap(rhs).

This function template does not participate in overload resolution unless std::is_move_constructible_v <T> and std::is_swappable_v <T> are both true.

### Parameters

lhs, rhs | - | `optional` objects whose states to swap

### Return value

(none)

### Exceptions

`noexcept` specification:
noexcept(noexcept(lhs.swap(rhs)))

### Example

| This section is incomplete Reason: no example

### See also

swap | exchanges the contents (public member function)

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