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

.SH SYNOPSIS
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.PP
.PP
\fC#include <istream>\fP
.SS "Public Types"

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

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

.SS "template<\fBtypename\fP _CharT, \fBtypename\fP _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\&. 
.SH "Member Typedef Documentation"
.PP 
.SS "template<\fBtypename\fP _CharT , \fBtypename\fP _Traits > \fBtypedef\fP _Traits \fBstd::basic_istream\fP< _CharT, _Traits >::sentry::traits_type"

.PP
Easy access to dependent types\&. 
.SH "Constructor & Destructor Documentation"
.PP 
.SS "template<\fBtypename\fP _CharT , \fBtypename\fP _Traits > \fBstd::basic_istream\fP< _CharT, _Traits >::sentry::sentry (\fBbasic_istream\fP< _CharT, _Traits > & __is, bool __noskipws = \fC\fBfalse\fP\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
References \fBstd::ios_base::badbit\fP, \fBstd::ios_base::eofbit\fP, \fBstd::ios_base::failbit\fP, \fBstd::ios_base::goodbit\fP, and \fBstd::ios_base::skipws\fP\&.
.SH "Member Function Documentation"
.PP 
.SS "template<\fBtypename\fP _CharT , \fBtypename\fP _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)\&. 

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