Performs setup work for output streams. More...
Objects of this class are created before all of the standard inserters are run. It is responsible for "exception-safe prefix and suffix operations." Additional actions may be added by the implementation, and we list them in http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5 under [27.6] notes.
Definition at line 355 of file ostream.
sentry | ( | basic_ostream< _CharT, _Traits > & | __os | ) | [inline, explicit] |
The constructor performs preparatory work.
os | The output stream to guard. |
If the stream state is good (os.good() is true), then if the stream is tied to another output stream, is.tie()->flush()
is called to synchronize the output sequences.
If the stream state is still good, then the sentry state becomes true ("okay").
Definition at line 51 of file ostream.tcc.
References ios_base::failbit, basic_ios< _CharT, _Traits >::good(), basic_ios< _CharT, _Traits >::setstate(), and basic_ios< _CharT, _Traits >::tie().
~sentry | ( | ) | [inline] |
Possibly flushes the stream.
If ios_base::unitbuf
is set in os.flags()
, and std::uncaught_exception()
is true, the sentry destructor calls flush()
on the output stream.
Definition at line 383 of file ostream.
References ios_base::badbit, std::uncaught_exception(), and ios_base::unitbuf.
operator bool | ( | ) | const [inline] |