# std::nullopt

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< cpp‎ | utility‎ | optional

Defined in header `<optional>` |  |
inline constexpr nullopt_t nullopt{/*unspecified*/}; |  | (since C++17)

`std::nullopt` is a constant of type std::nullopt_t. Used to indicate that an `std::optional` does not contain a value.

### See also

nullopt_t (C++17) | indicator of an `std::optional` that does not contain a value (class)

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