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

From cppreference.net
C++
Utilities library
std::expected
constexpr const E & error ( ) const & noexcept ;
(1) (since C++23)
constexpr E & error ( ) & noexcept ;
(2) (since C++23)
constexpr const E && error ( ) const && noexcept ;
(3) (since C++23)
constexpr E && error ( ) && noexcept ;
(4) (since C++23)

Accesses the unexpected value contained in * this .

If has_value() is true , the behavior is undefined.

(until C++26)

If has_value() is true :

  • If the implementation is hardened , a contract violation occurs. Moreover, if the contract-violation handler returns under “observe” evaluation semantic, the behavior is undefined.
  • If the implementation is not hardened, the behavior is undefined.
(since C++26)

Return value

1,2) unex
3,4) std :: move ( unex  )

Example

This section is incomplete
Reason: no example

See also

returns the unexpected value if present, another value otherwise
(public member function)
accesses the expected value
(public member function)
returns the expected value
(public member function)
checks whether the object contains an expected value
(public member function)