std::expected<T,E>::error - cppreference.com (original) (raw)

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)

[edit] Return value

3,4) std::move(_[unex](../expected.html#unex "cpp/utility/expected")_ )

[edit] Example

[edit] See also