std::expected<T,E>::value_or

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< cpp‎ | utility‎ | expected
 
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std::expected
 
template< class U >
constexpr T value_or( U&& default_value ) const&;
 (1) (since 哋它亢++23)
template< class U >
constexpr T value_or( U&& default_value ) &&;
 (2) (since 哋它亢++23)

Returns the contained value if *this contains an expected value, otherwise returns default_value.

1) Returns bool(*this) ? **this : static_cast<T>(std::forward<U>(default_value))
2) Returns bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(default_value))

Parameters

default_value - the value to use in case *this does not contain an expected value
Type requirements
-
T must meet the requirements of CopyConstructible in order to use overload (1).
-
T must meet the requirements of MoveConstructible in order to use overload (2).
-
U&& must be convertible to T

Return value

The currently contained value if *this contains an expected value, or default_value otherwise.

Exceptions

Any exception thrown by the selected constructor of the return value T.

Notes

If T is (possibly cv-qualified) void, this member is not declared.

Example

This section is incomplete
Reason: no example

See also

 returns the expected value
(public member function)
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