std::nullopt

From cppreference.com
< cpp‎ | utility‎ | optional
C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Integer comparison functions
(C++20)(C++20)(C++20)
(C++20)
Swap and type operations
(C++20)
(C++14)
(C++11)
(C++23)
(C++11)
(C++23)
(C++11)
(C++11)
(C++17)
Common vocabulary types
(C++11)
(C++17)
(C++17)
(C++17)
(C++11)
(C++11)
(C++17)
(C++17)
(C++23)



std::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

(C++17)
 indicator of an std::optional that does not contain a value
(class)
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/utility/optional/nullopt&oldid=172374