20 General utilities library [utilities]

20.6 Optional objects [optional]

20.6.5 Class bad_­optional_­access [optional.bad.access]

class bad_optional_access : public exception {
The class bad_­optional_­access defines the type of objects thrown as exceptions to report the situation where an attempt is made to access the value of an optional object that does not contain a value.
Effects: Constructs an object of class bad_­optional_­access.
Ensures: what() returns an implementation-defined ntbs.