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    <TITLE>Class Template basic_stdio_filter</TITLE>
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    <H1 CLASS="title">Class Template <CODE>basic_stdio_filter</CODE></H1>
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<DL class="page-index">
  <DT><A href="#description">Description</A></DT>
  <DT><A href="#headers">Headers</A></DT>
  <DT><A href="#reference">Reference</A></DT>
  <DT><A href="#example">Example</A></DT>
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<A NAME="description"></A>
<H2>Description</H2>

<P>
    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.
</P>
<P>
    <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.
</P>

<A NAME="headers"></A>
<H2>Headers</H2>

<DL class="page-index">
  <DT><A CLASS="header" HREF="../../../../boost/iostreams/filter/stdio.hpp"><CODE>&lt;boost/iostreams/filter/stdio.hpp&gt;</CODE></A></DT>
</DL>

<A NAME="reference"></A>
<H2>Reference</H2>

<H4>Synopsis</H4>

<PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {

<SPAN CLASS='keyword'>template</SPAN>&lt;<SPAN CLASS='keyword'>typename</SPAN> <A CLASS='documented' HREF='#template_params'>Ch</A>&gt;
<SPAN CLASS='keyword'>class</SPAN> <A CLASS='documented' HREF='#template_params'>basic_stdio_filter</A> {
<SPAN CLASS='keyword'>public:</SPAN>
    <SPAN CLASS='keyword'>typedef</SPAN> Ch                        char_type;
    <SPAN CLASS='keyword'>typedef</SPAN> <SPAN CLASS='omitted'>[implementation-defined]</SPAN>  category;
<SPAN CLASS='keyword'>protected:</SPAN>
    basic_stdio_filter();
<SPAN CLASS='keyword'>public:</SPAN>
    <SPAN CLASS='keyword'>virtual</SPAN> ~basic_stdio_filter();
<SPAN CLASS='keyword'>private:</SPAN>
    <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>;
};

<SPAN CLASS='keyword'>typedef</SPAN> basic_stdio_filter&lt;<SPAN CLASS='keyword'>char</SPAN>&gt;     <SPAN CLASS='defined'>stdio_filter</SPAN>;
<SPAN CLASS='keyword'>typedef</SPAN> basic_stdio_filter&lt;<SPAN CLASS='keyword'>wchar_t</SPAN>&gt;  <SPAN CLASS='defined'>wstdio_filter</SPAN>;

} } <SPAN CLASS="comment">// End namespace boost::io</SPAN></PRE>

<A NAME="template_params"></A>
<H4>Template parameters</H4>

<TABLE STYLE="margin-left:2em" BORDER=0 CELLPADDING=2>
<TR>
    <TR>
        <TD VALIGN="top"><I>Ch</I></TD><TD WIDTH="2em" VALIGN="top">-</TD>
        <TD>The <A HREF='../guide/traits.html#char_type'>character type</A></TD>
    </TR>
</TABLE>

<A NAME="do_filter"></A>
<H4><CODE>counter::do_filter</CODE></H4>

<PRE CLASS="broken_ie">    <SPAN CLASS='keyword'>virtual</SPAN> <SPAN CLASS='keyword'>void</SPAN> do_filter() <SPAN CLASS='numeric_literal'>= 0</SPAN>;</PRE>

<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>

<A NAME="example"></A>
<H2>Example</H2>

<P>Five examples of <CODE>stdio_filter</CODE>s are presented in the <A HREF="../tutorial/writing_filters.html">Tutorial</A>.</P>
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<P CLASS="copyright">&copy; Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>&copy; Copyright 2004-2007 <a href="https://www.boost.org/users/people/jonathan_turkanis.html" target="_top">Jonathan Turkanis</a></P>
<P CLASS="copyright"> 
    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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