std::basic_istream::sentry(3)std::basic_istream::sentry(3)NAME
std::basic_istream::sentry -
Performs setup work for input streams.
SYNOPSIS
Public Types
typedef __istream_type::__ctype_type __ctype_type
typedef _Traits::int_type __int_type
typedef basic_istream< _CharT, _Traits > __istream_type
typedef basic_streambuf< _CharT, _Traits > __streambuf_type
typedef _Traits traits_type
Public Member Functions
operator bool () const
sentry (basic_istream< _CharT, _Traits > &__is, bool __noskipws=false)
Detailed Description
template<typename _CharT, typename _Traits> class std::basic_istream<
_CharT, _Traits >::sentry
Performs setup work for input streams.
Objects of this class are created before all of the standard extractors
are run. It is responsible for 'exception-safe prefix and
suffix operations,' although only prefix actions are currently
required by the standard.
Definition at line 632 of file istream.
Member Typedef Documentation
template<typename _CharT, typename _Traits> typedef _Traits
std::basic_istream< _CharT, _Traits >::sentry::traits_type
Easy access to dependant types.
Definition at line 636 of file istream.
Constructor & Destructor Documentation
template<typename _CharT, typename _Traits> std::basic_istream< _CharT,
_Traits >::sentry::sentry (basic_istream< _CharT, _Traits > & __is,
bool __noskipws = false) [inline, explicit]
The constructor performs all the work. Parameters:
is The input stream to guard.
noskipws Whether to consume whitespace or not.
If the stream state is good (is.good() is true), then the following
actions are performed, otherwise the sentry state is false ('not okay')
and failbit is set in the stream state.
The sentry's preparatory actions are:
1. if the stream is tied to an output stream, is.tie()->flush() is
called to synchronize the output sequence
2. if noskipws is false, and ios_base::skipws is set in is.flags(),
the sentry extracts and discards whitespace characters from the
stream. The currently imbued locale is used to determine whether
each character is whitespace.
If the stream state is still good, then the sentry state becomes true
('okay').
Definition at line 47 of file istream.tcc.
References std::__ctype_abstract_base< _CharT >::is(),
std::basic_streambuf< _CharT, _Traits >::sgetc(), std::skipws(), and
std::basic_streambuf< _CharT, _Traits >::snextc().
Member Function Documentation
template<typename _CharT, typename _Traits> std::basic_istream< _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 673 of file istream.
Author
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libstdc++ 22 Nov 2013 std::basic_istream::sentry(3)
