std::basic_ostream< _CharT, _Traits >::sentry Class Reference

Performs setup work for output streams. More...

List of all members.

Public Member Functions
	sentry (basic_ostream< _CharT, _Traits > &__os)
	The constructor performs preparatory work.
	~sentry ()
	Possibly flushes the stream.
	operator bool () const
	Quick status checking.
Private Attributes
bool	_M_ok
basic_ostream< _CharT, _Traits > &	_M_os

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Detailed Description

template<typename _CharT, typename _Traits>
class std::basic_ostream< _CharT, _Traits >::sentry

Performs setup work for output streams.

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.

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Constructor & Destructor Documentation

template<typename _CharT, typename _Traits>

std::basic_ostream< _CharT, _Traits >::sentry::sentry

(

basic_ostream< _CharT, _Traits > &

__os

)

[explicit]

The constructor performs preparatory work.

Parameters:

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 std::basic_ostream< _CharT, _Traits >::sentry::_M_ok, std::ios_base::failbit, std::basic_ios< _CharT, _Traits >::good(), std::basic_ios< _CharT, _Traits >::setstate(), and std::basic_ios< _CharT, _Traits >::tie().

template<typename _CharT, typename _Traits>

std::basic_ostream< _CharT, _Traits >::sentry::~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 std::ios_base::badbit, std::uncaught_exception(), and std::ios_base::unitbuf.

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Member Function Documentation

template<typename _CharT, typename _Traits>

std::basic_ostream< _CharT, _Traits >::sentry::operator bool

(

)

const [inline]

Quick status checking.

Returns:

The sentry state.

For ease of use, sentries may be converted to booleans. The return value is that of the sentry state (true == okay).

Definition at line 401 of file ostream.

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Member Data Documentation

template<typename _CharT, typename _Traits>

bool std::basic_ostream< _CharT, _Traits >::sentry::_M_ok [private]

Definition at line 358 of file ostream.

Referenced by std::basic_ostream< _CharT, _Traits >::sentry::sentry().

template<typename _CharT, typename _Traits>

basic_ostream<_CharT,_Traits>& std::basic_ostream< _CharT, _Traits >::sentry::_M_os [private]

Definition at line 359 of file ostream.

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The documentation for this class was generated from the following files:

• ostream
• ostream.tcc

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