std::nullopt_t

Header: <optional>

std::nullopt_t is an empty class type used to indicate that an std::optional does not contain a value.

# Declarations

struct nullopt_t;

(since C++17)

# Notes

The constraints on nullopt_t’s constructors exist to support both op = {}; and op = nullopt; as the syntax for disengaging an optional object.

A possible implementation of this class is

# See also

• nullopt