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  <title>Boost &quot;quoted&quot; I/O manipulator</title>
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      <h1 align="center">&quot;Quoted&quot;
      I/O Manipulators<br>
      for Strings</h1>
      </td>
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    <td>
    <p align="center"><b>&quot;Quoted&quot;
      I/O Manipulators
      for Strings are not yet accepted into Boost as public components. Thus the 
    header file is currently located in &lt;boost/io/detail/quoted_manip.hpp&gt;</b></td>
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<h2>Introduction</h2>
<p>C++ Standard library stream I/O for strings that contain embedded spaces 
can produce unexpected results. For example,</p>
<blockquote>
  <pre>std::stringstream ss;
std::string original = &quot;fooled you&quot;;
std::string round_trip;

ss &lt;&lt; original;
ss &gt;&gt; round_trip;

std::cout &lt;&lt; original;   // outputs: fooled you
std::cout &lt;&lt; round_trip; // outputs: fooled

assert(original == round_trip); // assert will fire</pre>
</blockquote>
<p>The Boost <code>quoted</code> stream I/O manipulator places delimiters, defaulted 
to the double-quote (<code>&quot;</code>), around strings on output, and strips off 
the delimiters on input. This ensures strings with embedded spaces round-trip as 
desired. For example,</p>
<blockquote>
  <pre>std::stringstream ss;
std::string original = &quot;fooled you&quot;;
std::string round_trip;

ss &lt;&lt; quoted(original);
ss &gt;&gt; quoted(round_trip);

std::cout &lt;&lt; quoted(original); // outputs: &quot;fooled you&quot;
std::cout &lt;&lt; round_trip;       // outputs: fooled you

assert(original == round_trip); // assert will not fire</pre>
</blockquote>
<p>If the string contains the delimiter character, on output that character will 
be preceded by an escape character, as will the escape character itself:</p>
<blockquote>
  <pre>std::cout &lt;&lt; quoted(&quot;'Jack &amp; Jill'&quot;, '&amp;', '\'');  // outputs: '&amp;'Jack &amp;&amp; Jill&amp;''</pre>
</blockquote>
<h2>Header <a href="../../../boost/io/detail/quoted_manip.hpp">&lt;boost/io/quoted_manip.hpp&gt;</a> synopsis</h2>
<pre>namespace boost
{
  namespace io
  {
    // manipulator for const std::basic_string&amp;

    template &lt;class Char, class Traits, class Alloc&gt;
    <b><i>unspecified-type1</i></b> quoted(const std::basic_string&lt;Char, Traits, Alloc&gt;&amp; string,
                             Char escape='\\', Char delim='\&quot;');

    // manipulator for const C-string*

    template &lt;class Char&gt;
    <b><i>unspecified-type2</i></b> quoted(const Char* string,
                             Char escape='\\', Char delim='\&quot;');

    // manipulator for non-const std::basic_string&amp;

    template &lt;class Char, class Traits, class Alloc&gt;
    <b><i>unspecified-type3</i></b> quoted(std::basic_string&lt;Char, Traits, Alloc&gt;&amp; string,
                             Char escape='\\', Char delim='\&quot;');
  }
}</pre>
<p><i><b><code>unspecified_type1</code></b></i>, <i><b><code>unspecified_type2</code></b></i>, 
and <i><b><code>unspecified_type3</code></b></i> are implementation supplied 
types with implementation supplied <code>operator&lt;&lt;</code>:</p>
<blockquote>
  <pre>template &lt;class Char, class Traits&gt;
  std::basic_ostream&lt;Char, Traits&gt;&amp;
    operator&lt;&lt;(std::basic_ostream&lt;Char, Traits&gt;&amp; os, const <i><b><code>unspecified_typeN</code></b></i>&amp; proxy);</pre>
<p><i>Effects:</i> Inserts characters into <code>os</code>:</p>
  <ul>
    <li><code>delim</code>.</li>
    <li>Each character in <code>string</code>. If the character to be output is 
    equal to <code>escape</code> or <code>delim</code>, as determined by <code>
    operator==</code>, first output <code>escape</code>. </li>
    <li><code>delim</code>.</li>
  </ul>
<p><i>Remarks:</i> <code>string</code>, <code>escape</code>, and <code>delim</code> 
have the type and value of the corresponding arguments of the call to the <code>
quoted</code> function that constructed <code>proxy</code>.</p>
<p><i>Returns:</i> <code>os</code>. </p>
</blockquote>
<p><i><b><code>unspecified_type3</code></b></i> is an implementation supplied 
type with an implementation supplied <code>operator&gt;&gt;</code>:</p>
<blockquote>
  <pre>template &lt;class Char, class Traits&gt;
  std::basic_istream&lt;Char, Traits&gt;&amp;
    operator&gt;&gt;(std::basic_istream&lt;Char, Traits&gt;&amp; is, const <i><b><code>unspecified_type3</code></b></i>&amp; proxy);</pre>
<p><i>Effects:</i> Extracts characters from <code>os</code>:</p>
  <ul>
    <li>If the first character extracted is equal to delim, as determined by
    <code>operator==</code>, then:<ul>
      <li>Turn off the <code>skipws</code> flag.</li>
      <li><code>string.clear()</code></li>
      <li>Until an unescaped <code>delim</code> character is reached or <code>
      is.not_good()</code>, extract 
      characters from <code>os</code> and append them to <code>string</code>, 
      except that if an <code>escape</code> is reached, ignore it and append the 
      next character to <code>string</code>.</li>
      <li>Discard the final <code>delim</code> character.</li>
      <li>Restore the <code>skipws</code> flag to its original value.</li>
    </ul>
    </li>
    <li>Otherwise, <code>os &gt;&gt; string</code>.</li>
  </ul>
<p><i>Remarks:</i> <code>string</code>, <code>escape</code>, and <code>delim</code> 
have the type and value of the corresponding arguments of the call to the <code>
quoted</code> function that constructed <code>proxy</code>.</p>
<p><i>Returns:</i> <code>is</code>. </p>
</blockquote>
<h2>Acknowledgements</h2>
<p>The <code>quoted()</code> stream manipulator emerged from discussions on the 
Boost developers mailing list. Participants included Beman Dawes, Rob Stewart, 
Alexander Lamaison, Eric Niebler, Vicente Botet, Andrey Semashev, Phil Richards, 
and Rob Murray. Eric Niebler's suggestions provided the basis for the name and 
form of the templates. </p>
<hr>
<p>© Copyright Beman Dawes, 2002, 2006, 2007, 2009, 2010</p>
<p>Distributed under the Boost Software License, Version 1.0. See
<a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a></p>
<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B %Y" startspan -->08 March 2013<!--webbot bot="Timestamp" endspan i-checksum="27284" --></p>

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