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

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C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
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 , the program is ill-formed.
2) If std:: is_move_constructible_v < T > or std:: is_convertible_v < U, T > is false , the program is ill-formed.

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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