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

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std::expected
Primary template
template < class U >
constexpr T value_or( U&& default_value ) const & ;
(1) (since C++23)
template < class U >
constexpr T value_or( U&& default_value ) && ;
(2) (since C++23)

Returns the expected value if it exists, otherwise returns default_value.

The void partial specialization does not have these member functions.

1) If std::is_copy_constructible_v<T> or std::is_convertible_v<U, T> is false
2) If std::is_move_constructible_v<T> or std::is_convertible_v<U, T> is false

Parameters

default_value - the value to use in case *this does not contain an expected value

Return value

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

Example

This section is incomplete
Reason: no example

See also

 returns the expected value
(public member function)
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