# std::unexpect_t, std::unexpect

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< cpp‎ | utility‎ | expected

Defined in header `<expected>` |  |
struct unexpect_t { explicit unexpect_t() = default; }; | (1) | (since C++23)
inline constexpr std::unexpect_t unexpect{}; | (2) | (since C++23)

1) A tag type for in-place construction of an unexpected value in an `std::expected` object.
2) A constant of type const std::unexpect_t which is usually directly passed to a constructor of `std::expected` to construct an unexpected value.

### Notes

Like other construction tag types, `unexpect_t` is a trivial, empty class with an explicit default constructor.

### See also

(constructor) | constructs the `expected` object (public member function)
in_placein_place_typein_place_indexin_place_tin_place_type_tin_place_index_t (C++17) | in-place construction tag (tag)

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