.TH "std::basic_istream< _CharT, _Traits >::sentry" 3cxx "Mon May 22 2017" "libstdc++" \" -*- nroff -*-
.ad l
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.SH NAME
std::basic_istream< _CharT, _Traits >::sentry \- Performs setup work for input streams\&.  

.SH SYNOPSIS
.br
.PP
.SS "Public Types"

.in +1c
.ti -1c
.RI "typedef \fB__istream_type::__ctype_type\fP \fB__ctype_type\fP"
.br
.ti -1c
.RI "typedef _Traits::int_type \fB__int_type\fP"
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.ti -1c
.RI "typedef \fBbasic_istream\fP< _CharT, _Traits > \fB__istream_type\fP"
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.ti -1c
.RI "typedef \fBbasic_streambuf\fP< _CharT, _Traits > \fB__streambuf_type\fP"
.br
.ti -1c
.RI "typedef _Traits \fBtraits_type\fP"
.br
.RI "Easy access to dependent types\&. "
.in -1c
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "\fBsentry\fP (\fBbasic_istream\fP< _CharT, _Traits > &__is, bool __noskipws=false)"
.br
.RI "The constructor performs all the work\&. "
.ti -1c
.RI "\fBoperator bool\fP () const"
.br
.RI "Quick status checking\&. "
.in -1c
.SH "Detailed Description"
.PP 

.SS "template<typename _CharT, typename _Traits>
.br
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 \fIexception-safe prefix and suffix operations,\fP although only prefix actions are currently required by the standard\&. 
.PP
Definition at line 686 of file istream\&.
.SH "Member Typedef Documentation"
.PP 
.SS "template<typename _CharT, typename _Traits> typedef _Traits \fBstd::basic_istream\fP< _CharT, _Traits >::\fBsentry::traits_type\fP"

.PP
Easy access to dependent types\&. 
.PP
Definition at line 693 of file istream\&.
.SH "Constructor & Destructor Documentation"
.PP 
.SS "template<typename _CharT, typename _Traits> \fBstd::basic_istream\fP< _CharT, _Traits >::sentry::sentry (\fBbasic_istream\fP< _CharT, _Traits > & __is, bool __noskipws = \fCfalse\fP)\fC [explicit]\fP"

.PP
The constructor performs all the work\&. 
.PP
\fBParameters:\fP
.RS 4
\fI__is\fP The input stream to guard\&. 
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\fI__noskipws\fP Whether to consume whitespace or not\&.
.RE
.PP
If the stream state is good (\fI__is\&.good()\fP is true), then the following actions are performed, otherwise the sentry state is false (\fInot okay\fP) and failbit is set in the stream state\&.
.PP
The sentry's preparatory actions are:
.PP
.IP "1." 4
if the stream is tied to an output stream, \fCis\&.tie()->flush()\fP is called to synchronize the output sequence
.IP "2." 4
if \fI__noskipws\fP is false, and \fCios_base::skipws\fP is set in \fCis\&.flags()\fP, the sentry extracts and discards whitespace characters from the stream\&. The currently imbued locale is used to determine whether each character is whitespace\&.
.PP
.PP
If the stream state is still good, then the sentry state becomes true (\fIokay\fP)\&. 
.PP
Definition at line 47 of file istream\&.tcc\&.
.PP
References std::ios_base::eofbit, std::ios_base::failbit, std::ios_base::flags(), std::basic_ios< _CharT, _Traits >::good(), std::ios_base::goodbit, std::__ctype_abstract_base< _CharT >::is(), std::basic_ios< _CharT, _Traits >::rdbuf(), std::basic_ios< _CharT, _Traits >::setstate(), std::basic_streambuf< _CharT, _Traits >::sgetc(), std::ios_base::skipws, std::basic_streambuf< _CharT, _Traits >::snextc(), and std::basic_ios< _CharT, _Traits >::tie()\&.
.PP
Referenced by std::basic_istream< char >::get(), std::basic_istream< char >::getline(), std::basic_istream< char >::ignore(), std::basic_istream< char >::operator>>(), std::basic_istream< char >::peek(), std::basic_istream< char >::putback(), std::basic_istream< char >::read(), std::basic_istream< char >::readsome(), std::basic_istream< char >::seekg(), std::basic_istream< char >::sync(), std::basic_istream< char >::tellg(), and std::basic_istream< char >::unget()\&.
.SH "Member Function Documentation"
.PP 
.SS "template<typename _CharT, typename _Traits> \fBstd::basic_istream\fP< _CharT, _Traits >::sentry::operator bool () const\fC [inline]\fP, \fC [explicit]\fP"

.PP
Quick status checking\&. 
.PP
\fBReturns:\fP
.RS 4
The sentry state\&.
.RE
.PP
For ease of use, sentries may be converted to booleans\&. The return value is that of the sentry state (true == okay)\&. 
.PP
Definition at line 734 of file istream\&.

.SH "Author"
.PP 
Generated automatically by Doxygen for libstdc++ from the source code\&.