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std::bad_optional_access(3)   C++ Standard Libary  std::bad_optional_access(3)

NAME
       std::bad_optional_access	- std::bad_optional_access

Synopsis
	  Defined in header <optional>
	  class	bad_optional_access;	(since C++17)

	  Defines  a  type of object to	be thrown by std::optional::value when
       accessing an
	  optional object that does not	contain	a value.

	  std-bad optional access-inheritance-lwg2806.svg

					  Inheritance diagram

Member functions
	  constructor	constructs a new bad_optional_access object
			(public	member function)
	  operator=	replaces the bad_optional_access object
			(public	member function)
	  what		returns	the explanatory	string
			(public	member function)

       std::bad_optional_access::bad_optional_access

	  bad_optional_access()					     noexcept;
       (1) (since C++17)
	  bad_optional_access(	const  bad_optional_access&  other ) noexcept;
       (2) (since C++17)

	  Constructs a new bad_optional_access object with an  implementation-
       defined
	  null-terminated byte string which is accessible through what().

	  1) Default constructor.
	  2) Copy constructor. If *this	and other both have dynamic type
	  std::bad_optional_access  then  std::strcmp(what(), other.what()) ==
       0.

Parameters
	  other	- another exception object to copy

       std::bad_optional_access::operator=

	  bad_optional_access& operator=( const	bad_optional_access&  other  )
       (since C++17)
	  noexcept;

	  Assigns  the	contents  with those of	other. If *this	and other both
       have dynamic type
	  std::bad_optional_access then	std::strcmp(what(), other.what()) == 0
       after
	  assignment.

Parameters
	  other	- another exception object to assign with

Return value
	  *this

       std::bad_optional_access::what

	  virtual const	char* what() const noexcept;  (since C++17)

	  Returns the explanatory string.

Parameters
	  (none)

Return value
	  Pointer to a null-terminated string  with  explanatory  information.
       The string is
	  suitable  for	 conversion and	display	as a std::wstring. The pointer
       is guaranteed to
	  be valid at least until the exception	object from which  it  is  ob-
       tained is destroyed,
	  or until a non-const member function (e.g. copy assignment operator)
       on the
	  exception object is called.

Notes
	  Implementations are allowed but not required to override what().

       Inherited from std::exception

Member functions
	  destructor   destroys	the exception object
	  [virtual]    (virtual	public member function of std::exception)
	  what	       returns an explanatory string
	  [virtual]    (virtual	public member function of std::exception)

http://cppreference.com		  2022.07.31	   std::bad_optional_access(3)

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