std::ios_base::iostate exceptions() const;
void exceptions( std::ios_base::iostate except );
Gets and sets the exception mask of the stream. The exception mask determines the error states, on occurrence of which the stream throws exception of type failure.
1) Returns the exception mask.
2) Sets the exception mask to
 Return value
1) The current exception mask.
|This section is incomplete|
Reason: discuss LWG2349 and link from ios_base::clear, and from (un)formatted(i/o)utputfunction concept pages (or perhaps the behavior should be fully elaborated on the concepts pages and linked from here). See also stackoverflow.com/a/35089910