1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 2<HTML> 3<HEAD> 4 <TITLE>Class Template basic_stdio_filter</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">Class Template <CODE>basic_stdio_filter</CODE></H1> 13 <HR CLASS="banner"> 14 15<!-- End Banner --> 16 17<DL class="page-index"> 18 <DT><A href="#description">Description</A></DT> 19 <DT><A href="#headers">Headers</A></DT> 20 <DT><A href="#reference">Reference</A></DT> 21 <DT><A href="#example">Example</A></DT> 22</DL> 23 24<HR> 25 26<A NAME="description"></A> 27<H2>Description</H2> 28 29<P> 30 The class template <CODE>basic_stdio_filter</CODE> is a <A HREF='../concepts/dual_use_filter.html'>DualUseFilter</A> for use as a base class by Filters which read unfiltered data from standard input and write filtered data to standard output. 31</P> 32<P> 33 <CODE>basic_stdio_filter</CODE> is implemented by redirecting <CODE>std::cin</CODE> and <CODE>std::cout</CODE> (or <CODE>std::wcin</CODE> and <CODE>std::wcout</CODE>). Before <CODE>do_filter</CODE> is invoked, the entire stream of unfiltered data is read and stored in memory. As a result, <CODE>basic_stdio_filter</CODE> is unsuitable for use in low-memory environments or in conjunction with streams of data that have no natural end, such as stock tickers. Because of these limitations, <CODE>basic_stdio_filter</CODE> is best used as an aid to those learning to use the Iostreams library. 34</P> 35 36<A NAME="headers"></A> 37<H2>Headers</H2> 38 39<DL class="page-index"> 40 <DT><A CLASS="header" HREF="../../../../boost/iostreams/filter/stdio.hpp"><CODE><boost/iostreams/filter/stdio.hpp></CODE></A></DT> 41</DL> 42 43<A NAME="reference"></A> 44<H2>Reference</H2> 45 46<H4>Synopsis</H4> 47 48<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams { 49 50<SPAN CLASS='keyword'>template</SPAN><<SPAN CLASS='keyword'>typename</SPAN> <A CLASS='documented' HREF='#template_params'>Ch</A>> 51<SPAN CLASS='keyword'>class</SPAN> <A CLASS='documented' HREF='#template_params'>basic_stdio_filter</A> { 52<SPAN CLASS='keyword'>public:</SPAN> 53 <SPAN CLASS='keyword'>typedef</SPAN> Ch char_type; 54 <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN> category; 55<SPAN CLASS='keyword'>protected:</SPAN> 56 basic_stdio_filter(); 57<SPAN CLASS='keyword'>public:</SPAN> 58 <SPAN CLASS='keyword'>virtual</SPAN> ~basic_stdio_filter(); 59<SPAN CLASS='keyword'>private:</SPAN> 60 <SPAN CLASS='keyword'>virtual</SPAN> <SPAN CLASS='keyword'>void</SPAN> <A CLASS='documented' HREF='#do_filter'>do_filter</A>() <SPAN CLASS='numeric_literal'>= 0</SPAN>; 61}; 62 63<SPAN CLASS='keyword'>typedef</SPAN> basic_stdio_filter<<SPAN CLASS='keyword'>char</SPAN>> <SPAN CLASS='defined'>stdio_filter</SPAN>; 64<SPAN CLASS='keyword'>typedef</SPAN> basic_stdio_filter<<SPAN CLASS='keyword'>wchar_t</SPAN>> <SPAN CLASS='defined'>wstdio_filter</SPAN>; 65 66} } <SPAN CLASS="comment">// End namespace boost::io</SPAN></PRE> 67 68<A NAME="template_params"></A> 69<H4>Template parameters</H4> 70 71<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2> 72<TR> 73 <TR> 74 <TD VALIGN="top"><I>Ch</I></TD><TD WIDTH="2em" VALIGN="top">-</TD> 75 <TD>The <A HREF='../guide/traits.html#char_type'>character type</A></TD> 76 </TR> 77</TABLE> 78 79<A NAME="do_filter"></A> 80<H4><CODE>counter::do_filter</CODE></H4> 81 82<PRE CLASS="broken_ie"> <SPAN CLASS='keyword'>virtual</SPAN> <SPAN CLASS='keyword'>void</SPAN> do_filter() <SPAN CLASS='numeric_literal'>= 0</SPAN>;</PRE> 83 84<P>Reads from standard input and writes to standard output until standard input is exhausted. If <CODE>Ch</CODE> is <CODE>char</CODE>, uses <CODE>std::cin</CODE> and <CODE>std::cout</CODE>; if <CODE>Ch</CODE> is <CODE>wchar_t</CODE>, uses <CODE>std::wcin</CODE> and <CODE>std::wcout</CODE>.</P> 85 86<A NAME="example"></A> 87<H2>Example</H2> 88 89<P>Five examples of <CODE>stdio_filter</CODE>s are presented in the <A HREF="../tutorial/writing_filters.html">Tutorial</A>.</P> 90<!-- Begin Footer --> 91 92<HR> 93 94<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> 95<P CLASS="copyright"> 96 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>) 97</P> 98 99<!-- End Footer --> 100 101</BODY> 102