<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Concept OutputIterator</title> <link rel="stylesheet" href="../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="id317761-bb.html#concepts.reference" title="Concept reference"> <link rel="prev" href="InputIterator.html" title="Concept InputIterator"> <link rel="next" href="ForwardIterator.html" title="Concept ForwardIterator"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr> <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../boost.png"></td> <td align="center"><a href="../../index.html">Home</a></td> <td align="center"><a href="../../libs/libraries.htm">Libraries</a></td> <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> <td align="center"><a href="../../more/index.htm">More</a></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="InputIterator.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="id317761-bb.html#concepts.reference"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="ForwardIterator.html"><img src="../../doc/src/images/next.png" alt="Next"></a> </div> <div class="refentry"> <a name="OutputIterator"></a><div class="titlepage"></div> <div class="refnamediv"> <h2><span class="refentrytitle">Concept OutputIterator</span></h2> <p>OutputIterator</p> </div> <div class="refsect1"> <a name="id1021203"></a><h2>Description</h2> <p>An output iterator is an iterator that can write a sequence of values. It is single-pass (old values of the iterator cannot be re-used), and write-only.</p> <p>An output iterator represents a position in a (possibly infinite) sequence. Therefore, the iterator can point into the sequence (returning a value when dereferenced and being incrementable), or be off-the-end (and not dereferenceable or incrementable).</p> </div> <div class="refsect1"> <a name="id1021221"></a><h2>Associated types</h2> <div class="itemizedlist"><ul class="itemizedlist" type="disc"> <li class="listitem"> <p><span class="bold"><strong>value_type</strong></span></p> <pre class="literallayout">std::iterator_traits<Iter>::value_type</pre> <p>The stated value type of the iterator (should be <code class="computeroutput">void</code> for an output iterator that does not model some other iterator concept).</p> </li> <li class="listitem"> <p><span class="bold"><strong>difference_type</strong></span></p> <pre class="literallayout">std::iterator_traits<Iter>::difference_type</pre> <p>The difference type of the iterator</p> </li> <li class="listitem"> <p><span class="bold"><strong>category</strong></span></p> <pre class="literallayout">std::iterator_traits<Iter>::iterator_category</pre> <p>The category of the iterator</p> </li> </ul></div> </div> <div class="refsect1"> <a name="id1021286"></a><h2>Notation</h2> <div class="variablelist"><dl> <dt><span class="term">Iter</span></dt> <dd>A type playing the role of iterator-type in the <a class="link" href="OutputIterator.html" title="Concept OutputIterator">OutputIterator</a> concept.</dd> <dt><span class="term">ValueType</span></dt> <dd>A type playing the role of value-type in the <a class="link" href="OutputIterator.html" title="Concept OutputIterator">OutputIterator</a> concept.</dd> <dt> <span class="term"><code class="varname">i</code>, </span><span class="term"><code class="varname">j</code></span> </dt> <dd>Objects of type Iter</dd> <dt><span class="term"><code class="varname">x</code></span></dt> <dd>Object of type ValueType</dd> </dl></div> </div> <div class="refsect1"> <a name="id1021338"></a><h2>Type expressions</h2> <div class="variablelist"><dl> <dt><span class="term"></span></dt> <dd><p>The type <span class="type">Iter</span> must be a model of <a class="link" href="Assignable.html" title="Concept Assignable">Assignable</a>.</p></dd> <dt><span class="term"></span></dt> <dd><p>The type <span class="type">ValueType</span> must be a model of <a class="link" href="Assignable.html" title="Concept Assignable">Assignable</a>.</p></dd> <dt><span class="term"></span></dt> <dd><p>The type <span class="type">Iter</span> must be a model of <a class="link" href="DefaultConstructible.html" title="Concept DefaultConstructible">DefaultConstructible</a>.</p></dd> <dt><span class="term"></span></dt> <dd><p>The type <span class="type">Iter</span> must be a model of <a class="link" href="EqualityComparable.html" title="Concept EqualityComparable">EqualityComparable</a>.</p></dd> <dt><span class="term">Category tag</span></dt> <dd><p><span class="type">category</span> must be derived from <span class="type">std::output_iterator_tag</span>, a model of <a class="link" href="DefaultConstructible.html" title="Concept DefaultConstructible">DefaultConstructible</a>, and a model of <a class="link" href="CopyConstructible.html" title="Concept CopyConstructible">CopyConstructible</a>. </p></dd> <dt><span class="term">Difference type properties</span></dt> <dd><p><span class="type">difference_type</span> must be a model of <a class="link" href="SignedInteger.html" title="Concept SignedInteger">SignedInteger</a>. </p></dd> </dl></div> </div> <div class="refsect1"> <a name="id1021456"></a><h2>Valid expressions</h2> <div class="informaltable"><table class="table"> <colgroup> <col> <col> <col> <col> <col> <col> </colgroup> <thead><tr> <th>Name</th> <th>Expression</th> <th>Type</th> <th>Precondition</th> <th>Semantics</th> <th>Postcondition</th> </tr></thead> <tbody> <tr> <td><p>Dereference</p></td> <td><p>*i</p></td> <td><p></p></td> <td><p><code class="computeroutput">i</code> is incrementable (not off-the-end)</p></td> <td> </td> <td> </td> </tr> <tr> <td><p>Dereference and assign</p></td> <td><p>*i = x</p></td> <td><p></p></td> <td><p><code class="computeroutput">i</code> is incrementable (not off-the-end)</p></td> <td> </td> <td><p><code class="computeroutput">*i</code> may not be written to again until it has been incremented.</p></td> </tr> <tr> <td><p>Preincrement</p></td> <td><p>++i</p></td> <td><p><span class="type">Iter &</span></p></td> <td><p><code class="computeroutput">i</code> is incrementable (not off-the-end)</p></td> <td> </td> <td> </td> </tr> <tr> <td><p>Postincrement</p></td> <td><p>i++</p></td> <td><p></p></td> <td><p><code class="computeroutput">i</code> is incrementable (not off-the-end)</p></td> <td><p>Equivalent to <code class="computeroutput">(void)(++i)</code></p></td> <td><p><code class="computeroutput">i</code> is dereferenceable or off-the-end</p></td> </tr> <tr> <td><p>Postincrement, dereference, and assign</p></td> <td><p>*i++ = x</p></td> <td><p></p></td> <td><p><code class="computeroutput">i</code> is incrementable (not off-the-end)</p></td> <td><p>Equivalent to <code class="computeroutput">{*i = t; ++i;}</code></p></td> <td><p><code class="computeroutput">i</code> is dereferenceable or off-the-end</p></td> </tr> </tbody> </table></div> </div> <div class="refsect1"> <a name="id1021622"></a><h2>Complexity</h2> <p> All iterator operations must take amortized constant time. </p> </div> <div class="refsect1"> <a name="id1021629"></a><h2>Models</h2> <div class="itemizedlist"><ul class="itemizedlist" type="disc"> <li class="listitem"><span class="simplelist"><span class="type">std::ostream_iterator</span>, <span class="type">...</span></span></li> <li class="listitem"><span class="simplelist"><span class="type">std::insert_iterator</span>, <span class="type">...</span></span></li> <li class="listitem"><span class="simplelist"><span class="type">std::front_insert_iterator</span>, <span class="type">...</span></span></li> <li class="listitem"><span class="simplelist"><span class="type">std::back_insert_iterator</span>, <span class="type">...</span></span></li> </ul></div> </div> </div> <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> <td align="left"></td> <td align="right"><div class="copyright-footer">Copyright © 2001, 2002 Indiana University<br>Copyright © 2000, 2001 University of Notre Dame du Lac<br>Copyright © 2000 Jeremy Siek, Lie-Quan Lee, Andrew Lumsdaine<br>Copyright © 1996-1999 Silicon Graphics Computer Systems, Inc.<br>Copyright © 1994 Hewlett-Packard Company<p>Distributed under the Boost Software License, Version 1.0. (See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) </p> <p>This product includes software developed at the University of Notre Dame and the Pervasive Technology Labs at Indiana University. For technical information contact Andrew Lumsdaine at the Pervasive Technology Labs at Indiana University. For administrative and license questions contact the Advanced Research and Technology Institute at 351 West 10th Street. Indianapolis, Indiana 46202, phone 317-278-4100, fax 317-274-5902.</p> <p>Some concepts based on versions from the MTL draft manual and Boost Graph and Property Map documentation, the SGI Standard Template Library documentation and the Hewlett-Packard STL, under the following license: </p> <div class="blockquote"><blockquote class="blockquote"><p>Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appears in all copies and that both that copyright notice and this permission notice appear in supporting documentation. Silicon Graphics makes no representations about the suitability of this software for any purpose. 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