1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<HTML> 3<HEAD> 4 <TITLE>File Wrappers</TITLE> 5 <LINK REL="stylesheet" HREF="../../../../boost.css"> 6 <LINK REL="stylesheet" HREF="../theme/iostreams.css"> 7</HEAD> 8<BODY> 9 10<!-- Begin Banner --> 11 12 <H1 CLASS="title">File Wrappers</H1> 13 <HR CLASS="banner"> 14 15<!-- End Banner --> 16 17<DL class="page-index"> 18 <DT><A href="#overview">Overview</A></DT> 19 <DT><A href="#headers">Headers</A></DT> 20 <DT><A href="#reference">Reference</A> 21 <UL> 22 <LI CLASS="square"><A href="#file_source">Class template <CODE>basic_file_source</CODE></A></LI> 23 <LI CLASS="square"><A href="#file_sink">Class template <CODE>basic_file_sink</CODE></A></LI> 24 <LI CLASS="square"><A href="#file">Class template <CODE>basic_file</CODE></A></LI> 25 </UL> 26 </DT> 27</DL> 28 29<HR> 30 31<A NAME="overview"></A> 32<H2>Overview</H2> 33 34<P> 35 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. 36</P> 37<P> 38 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>. 39</P> 40 41<A NAME="headers"></A> 42<H2>Headers</H2> 43 44<DL class="page-index"> 45 <DT><A CLASS="header" HREF="../../../../boost/iostreams/device/file.hpp"><CODE><boost/iostreams/device/file.hpp></CODE></A></DT> 46</DL> 47 48<A NAME="reference"></A> 49<H2>Reference</H2> 50 51<A NAME="file_source"></A> 52<H3>Class template <CODE>basic_file_source</CODE></H3> 53 54<H4>Description</H4> 55 56<P> 57 <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. 58<P> 59 60<A NAME="file_source_synopsis"></A> 61<H4>Synopsis</H4> 62 63<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { 64 65<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">Ch</A>> 66<SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">basic_file_source</A> { 67<SPAN CLASS="keyword">public</SPAN>: 68 <SPAN CLASS="keyword">typedef</SPAN> Ch char_type; 69 <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category; 70 <A CLASS="documented" HREF="#basic_file_source_constructor">basic_file_source</A>( <SPAN CLASS="keyword">const</SPAN> std::string& path, 71 std::ios_base::openmode mode = 72 std::ios_base::in ); 73 <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_source_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>; 74 <SPAN CLASS="omitted">...</SPAN> 75}; 76 77<SPAN CLASS="keyword">typedef</SPAN> basic_file_source<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">file_source</SPAN>; 78<SPAN CLASS="keyword">typedef</SPAN> basic_file_source<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wfile_source</SPAN>; 79 80} } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE> 81 82<A NAME="basic_file_source_params"></A> 83<H4>Template parameters</H4> 84 85<TABLE STYLE="margin-left:2em"> 86<TR> 87 <TD><I>Ch</I></TD><TD VALIGN="top">-</TD> 88 <TD>The character type.</TD></TR> 89<TR> 90</TABLE> 91 92<A NAME="basic_file_source_constructor"></A> 93<H4><CODE>basic_file_source::basic_file_source</CODE></H4> 94 95<PRE CLASS="broken_ie"> basic_file_source( <SPAN CLASS="keyword">const</SPAN> std::string& path, 96 std::ios_base::openmode mode );</PRE> 97 98<P> 99 Constructs a <CODE>basic_file_source</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows: 100 <PRE CLASS="broken_ie"> mode |= std::ios_base::in; 101 mode &= ~std::ios_base::out; 102 buf.open(path.c_str(), mode);</PRE> 103</P> 104 105<A NAME="basic_file_source_is_open"></A> 106<H4><CODE>basic_file_source::is_open</CODE></H4> 107 108<PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE> 109 110<P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P> 111 112<A NAME="file_sink"></A> 113<H3>Class template <CODE>basic_file_sink</CODE></H3> 114 115<H4>Description</H4> 116 117<P> 118 <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. 119<P> 120 121<A NAME="file_sink_synopsis"></A> 122<H4>Synopsis</H4> 123 124<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { 125 126<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">Ch</A>> 127<SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">basic_file_sink</A> { 128<SPAN CLASS="keyword">public</SPAN>: 129 <SPAN CLASS="keyword">typedef</SPAN> Ch char_type; 130 <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category; 131 <A CLASS="documented" HREF="#basic_file_sink_constructor">basic_file_sink</A>( <SPAN CLASS="keyword">const</SPAN> std::string& path, 132 std::ios_base::openmode mode = 133 std::ios_base::out ); 134 <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_sink_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>; 135 <SPAN CLASS="omitted">...</SPAN> 136}; 137 138<SPAN CLASS="keyword">typedef</SPAN> basic_file_sink<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">file_sink</SPAN>; 139<SPAN CLASS="keyword">typedef</SPAN> basic_file_sink<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wfile_sink</SPAN>; 140 141} } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE> 142 143<A NAME="basic_file_sink_params"></A> 144<H4>Template parameters</H4> 145 146<TABLE STYLE="margin-left:2em"> 147<TR> 148 <TD><I>Ch</I></TD><TD VALIGN="top">-</TD> 149 <TD>The character type.</TD></TR> 150<TR> 151</TABLE> 152 153<A NAME="basic_file_sink_constructor"></A> 154<H4><CODE>basic_file_sink::basic_file_sink</CODE></H4> 155 156<PRE CLASS="broken_ie"> basic_file_sink( <SPAN CLASS="keyword">const</SPAN> std::string& path, 157 std::ios_base::openmode mode );</PRE> 158 159<P> 160 Constructs a <CODE>basic_file_sink</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows: 161 <PRE CLASS="broken_ie"> mode |= std::ios_base::out; 162 mode &= ~std::ios_base::in; 163 buf.open(path.c_str(), mode);</PRE> 164</P> 165 166<A NAME="basic_file_sink_is_open"></A> 167<H4><CODE>basic_file_sink::is_open</CODE></H4> 168 169<PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE> 170 171<P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P> 172 173<A NAME="file"></A> 174<H3>Class template <CODE>basic_file</CODE></H3> 175 176<H4>Description</H4> 177 178<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. 179 180<A NAME="file_synopsis"></A> 181<H4>Synopsis</H4> 182 183<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { 184 185<SPAN CLASS="keyword">template</SPAN><<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_params">Ch</A>> 186<SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_params">basic_file</A> { 187<SPAN CLASS="keyword">public</SPAN>: 188 <SPAN CLASS="keyword">typedef</SPAN> Ch char_type; 189 <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category; 190 <A CLASS="documented" HREF="#basic_file_constructor">basic_file</A>( <SPAN CLASS="keyword">const</SPAN> std::string& path, 191 std::ios_base::openmode mode = 192 std::ios_base::in | std::ios_base::out ); 193 <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>; 194 <SPAN CLASS="omitted">...</SPAN> 195}; 196 197<SPAN CLASS="keyword">typedef</SPAN> basic_file<<SPAN CLASS="keyword">char</SPAN>> <SPAN CLASS="defined">file</SPAN>; 198<SPAN CLASS="keyword">typedef</SPAN> basic_file<<SPAN CLASS="keyword">wchar_t</SPAN>> <SPAN CLASS="defined">wfile</SPAN>; 199 200} } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE> 201 202<A NAME="basic_file_params"></A> 203<H4>Template parameters</H4> 204 205<TABLE STYLE="margin-left:2em"> 206<TR> 207 <TD><I>Ch</I></TD><TD VALIGN="top">-</TD> 208 <TD>The character type.</TD></TR> 209<TR> 210</TABLE> 211 212<A NAME="basic_file_constructor"></A> 213<H4><CODE>basic_file_::basic_file</CODE></H4> 214 215<PRE CLASS="broken_ie"> basic_file( <SPAN CLASS="keyword">const</SPAN> std::string& path, 216 std::ios_base::openmode mode );</PRE> 217 218<P> 219 Constructs a <CODE>basic_file</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows: 220 <PRE CLASS="broken_ie"> mode |= std::ios_base::in | std::ios_base::out; 221 buf.open(path.c_str(), mode);</PRE> 222</P> 223 224<A NAME="basic_file_is_open"></A> 225<H4><CODE>basic_file::is_open</CODE></H4> 226 227<PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE> 228 229<P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P> 230 231<!-- Begin Footer --> 232 233<HR> 234 235<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> 236<P CLASS="copyright"> 237 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>) 238</P> 239 240<!-- End Footer --> 241 242</BODY>