242 lines
11 KiB
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242 lines
11 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML>
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<HEAD>
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<TITLE>File Wrappers</TITLE>
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<LINK REL="stylesheet" HREF="../../../../boost.css">
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<LINK REL="stylesheet" HREF="../theme/iostreams.css">
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</HEAD>
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<BODY>
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<!-- Begin Banner -->
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<H1 CLASS="title">File Wrappers</H1>
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<HR CLASS="banner">
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<!-- End Banner -->
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<DL class="page-index">
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<DT><A href="#overview">Overview</A></DT>
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<DT><A href="#headers">Headers</A></DT>
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<DT><A href="#reference">Reference</A>
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<UL>
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<LI CLASS="square"><A href="#file_source">Class template <CODE>basic_file_source</CODE></A></LI>
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<LI CLASS="square"><A href="#file_sink">Class template <CODE>basic_file_sink</CODE></A></LI>
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<LI CLASS="square"><A href="#file">Class template <CODE>basic_file</CODE></A></LI>
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</UL>
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</DT>
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</DL>
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<HR>
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<A NAME="overview"></A>
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<H2>Overview</H2>
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<P>
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The class templates <CODE>basic_file_source</CODE>, <CODE>basic_file_sink</CODE> and <CODE>basic_file</CODE> are wrappers for <CODE>std::basic_filebuf</CODE> which are <A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A>. They are useful whenever one wants to access a file without managing the lifetime of a standard file stream or stream buffer. This is because when a stream or stream buffer is added to a <A HREF="filtering_streambuf.html"><CODE>filtering_streambuf</CODE></A> or <A HREF="filtering_stream.html"><CODE>filtering_stream</CODE></A> it is stored as a reference which must remain valid until that stream or stream buffer is removed from the chain.
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</P>
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<P>
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The most common specializations are accessible via the typedefs <CODE>file_source</CODE>, <CODE>file_sink</CODE>, <CODE>file</CODE>, <CODE>wfile_source</CODE>, <CODE>wfile_sink</CODE> and <CODE>wfile</CODE>.
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</P>
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<A NAME="headers"></A>
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<H2>Headers</H2>
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<DL class="page-index">
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<DT><A CLASS="header" HREF="../../../../boost/iostreams/device/file.hpp"><CODE><boost/iostreams/device/file.hpp></CODE></A></DT>
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</DL>
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<A NAME="reference"></A>
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<H2>Reference</H2>
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<A NAME="file_source"></A>
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<H3>Class template <CODE>basic_file_source</CODE></H3>
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<H4>Description</H4>
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<P>
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<A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in read-only mode.
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<P>
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<A NAME="file_source_synopsis"></A>
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<H4>Synopsis</H4>
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<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">Ch</A>>
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<SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">basic_file_source</A> {
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<SPAN CLASS="keyword">public</SPAN>:
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<SPAN CLASS="keyword">typedef</SPAN> Ch char_type;
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<SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category;
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<A CLASS="documented" HREF="#basic_file_source_constructor">basic_file_source</A>( <SPAN CLASS="keyword">const</SPAN> std::string& path,
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std::ios_base::openmode mode =
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std::ios_base::in );
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<SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_source_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
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<SPAN CLASS="omitted">...</SPAN>
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};
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<SPAN CLASS="keyword">typedef</SPAN> basic_file_source<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">file_source</SPAN>;
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<SPAN CLASS="keyword">typedef</SPAN> basic_file_source<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wfile_source</SPAN>;
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} } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
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<A NAME="basic_file_source_params"></A>
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<H4>Template parameters</H4>
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<TABLE STYLE="margin-left:2em">
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<TR>
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<TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
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<TD>The character type.</TD></TR>
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<TR>
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</TABLE>
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<A NAME="basic_file_source_constructor"></A>
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<H4><CODE>basic_file_source::basic_file_source</CODE></H4>
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<PRE CLASS="broken_ie"> basic_file_source( <SPAN CLASS="keyword">const</SPAN> std::string& path,
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std::ios_base::openmode mode );</PRE>
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<P>
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Constructs a <CODE>basic_file_source</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
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<PRE CLASS="broken_ie"> mode |= std::ios_base::in;
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mode &= ~std::ios_base::out;
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buf.open(path.c_str(), mode);</PRE>
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</P>
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<A NAME="basic_file_source_is_open"></A>
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<H4><CODE>basic_file_source::is_open</CODE></H4>
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<PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
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<P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
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<A NAME="file_sink"></A>
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<H3>Class template <CODE>basic_file_sink</CODE></H3>
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<H4>Description</H4>
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<P>
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<A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in write-only mode.
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<P>
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<A NAME="file_sink_synopsis"></A>
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<H4>Synopsis</H4>
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<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">Ch</A>>
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<SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">basic_file_sink</A> {
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<SPAN CLASS="keyword">public</SPAN>:
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<SPAN CLASS="keyword">typedef</SPAN> Ch char_type;
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<SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category;
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<A CLASS="documented" HREF="#basic_file_sink_constructor">basic_file_sink</A>( <SPAN CLASS="keyword">const</SPAN> std::string& path,
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std::ios_base::openmode mode =
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std::ios_base::out );
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<SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_sink_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
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<SPAN CLASS="omitted">...</SPAN>
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};
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<SPAN CLASS="keyword">typedef</SPAN> basic_file_sink<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">file_sink</SPAN>;
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<SPAN CLASS="keyword">typedef</SPAN> basic_file_sink<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wfile_sink</SPAN>;
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} } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
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<A NAME="basic_file_sink_params"></A>
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<H4>Template parameters</H4>
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<TABLE STYLE="margin-left:2em">
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<TR>
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<TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
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<TD>The character type.</TD></TR>
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<TR>
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</TABLE>
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<A NAME="basic_file_sink_constructor"></A>
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<H4><CODE>basic_file_sink::basic_file_sink</CODE></H4>
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<PRE CLASS="broken_ie"> basic_file_sink( <SPAN CLASS="keyword">const</SPAN> std::string& path,
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std::ios_base::openmode mode );</PRE>
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<P>
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Constructs a <CODE>basic_file_sink</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
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<PRE CLASS="broken_ie"> mode |= std::ios_base::out;
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mode &= ~std::ios_base::in;
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buf.open(path.c_str(), mode);</PRE>
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</P>
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<A NAME="basic_file_sink_is_open"></A>
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<H4><CODE>basic_file_sink::is_open</CODE></H4>
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<PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
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<P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
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<A NAME="file"></A>
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<H3>Class template <CODE>basic_file</CODE></H3>
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<H4>Description</H4>
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<P><A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in read-write mode by default.
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<A NAME="file_synopsis"></A>
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<H4>Synopsis</H4>
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<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
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<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_params">Ch</A>>
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<SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_params">basic_file</A> {
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<SPAN CLASS="keyword">public</SPAN>:
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<SPAN CLASS="keyword">typedef</SPAN> Ch char_type;
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<SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category;
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<A CLASS="documented" HREF="#basic_file_constructor">basic_file</A>( <SPAN CLASS="keyword">const</SPAN> std::string& path,
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std::ios_base::openmode mode =
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std::ios_base::in | std::ios_base::out );
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<SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
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<SPAN CLASS="omitted">...</SPAN>
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};
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<SPAN CLASS="keyword">typedef</SPAN> basic_file<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">file</SPAN>;
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<SPAN CLASS="keyword">typedef</SPAN> basic_file<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wfile</SPAN>;
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} } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
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<A NAME="basic_file_params"></A>
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<H4>Template parameters</H4>
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<TABLE STYLE="margin-left:2em">
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<TR>
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<TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
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<TD>The character type.</TD></TR>
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<TR>
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</TABLE>
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<A NAME="basic_file_constructor"></A>
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<H4><CODE>basic_file_::basic_file</CODE></H4>
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<PRE CLASS="broken_ie"> basic_file( <SPAN CLASS="keyword">const</SPAN> std::string& path,
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std::ios_base::openmode mode );</PRE>
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<P>
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Constructs a <CODE>basic_file</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
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<PRE CLASS="broken_ie"> mode |= std::ios_base::in | std::ios_base::out;
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buf.open(path.c_str(), mode);</PRE>
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</P>
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<A NAME="basic_file_is_open"></A>
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<H4><CODE>basic_file::is_open</CODE></H4>
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<PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
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<P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
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<!-- Begin Footer -->
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<P CLASS="copyright">© Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>© Copyright 2004-2007 <a href="https://www.boost.org/users/people/jonathan_turkanis.html" target="_top">Jonathan Turkanis</a></P>
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<P CLASS="copyright">
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Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <A HREF="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)
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