doc/html/InputIterator.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
   2 <html>
   3 <head>
   4 <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
   5 <title>Concept InputIterator</title>
   6 <link rel="stylesheet" href="../../doc/src/boostbook.css" type="text/css">
   7 <meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
   8 <link rel="home" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
   9 <link rel="up" href="idp14900640-bb.html#concepts.reference" title="Concept reference">
  10 <link rel="prev" href="Assignable.html" title="Concept Assignable">
  11 <link rel="next" href="OutputIterator.html" title="Concept OutputIterator">
  12 </head>
  13 <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
  14 <table cellpadding="2" width="100%"><tr>
  15 <td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../boost.png"></td>
  16 <td align="center"><a href="../../index.html">Home</a></td>
  17 <td align="center"><a href="../../libs/libraries.htm">Libraries</a></td>
  18 <td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
  19 <td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
  20 <td align="center"><a href="../../more/index.htm">More</a></td>
  21 </tr></table>
  22 <hr>
  23 <div class="spirit-nav">
  24 <a accesskey="p" href="Assignable.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="idp14900640-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="OutputIterator.html"><img src="../../doc/src/images/next.png" alt="Next"></a>
  25 </div>
  26 <div class="refentry">
  27 <a name="InputIterator"></a><div class="titlepage"></div>
  28 <div class="refnamediv">
  29 <h2><span class="refentrytitle">Concept InputIterator</span></h2>
  30 <p>InputIterator</p>
  31 </div>
  32 <div class="refsect1">
  33 <a name="idp634271104"></a><h2>Description</h2>
  34 <p>An input iterator is an iterator that can read through a sequence of
  35   values.  It is single-pass (old values of the iterator cannot be
  36   re-used), and read-only.</p>
  37 <p>An input iterator represents a position in a sequence.  Therefore, the
  38   iterator can point into the sequence (returning a value when dereferenced
  39   and being incrementable), or be off-the-end (and not dereferenceable or
  40   incrementable).</p>
  41 </div>
  42 <div class="refsect1">
  43 <a name="idp634272848"></a><h2>Refinement of</h2>
  44 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  45 <li class="listitem"><p><a class="link" href="Assignable.html" title="Concept Assignable">Assignable</a></p></li>
  46 <li class="listitem"><p><a class="link" href="DefaultConstructible.html" title="Concept DefaultConstructible">DefaultConstructible</a></p></li>
  47 <li class="listitem"><p><a class="link" href="EqualityComparable.html" title="Concept EqualityComparable">EqualityComparable</a></p></li>
  48 </ul></div>
  49 </div>
  50 <div class="refsect1">
  51 <a name="idp634276176"></a><h2>Associated types</h2>
  52 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
  53 <li class="listitem">
  54 <p><span class="bold"><strong>value_type</strong></span></p>
  55 <pre class="literallayout">std::iterator_traits&lt;Iter&gt;::value_type</pre>
  56 <p>The value type of the iterator (not necessarily what
  57     <code class="computeroutput">*i</code> returns)</p>
  58 </li>
  59 <li class="listitem">
  60 <p><span class="bold"><strong>difference_type</strong></span></p>
  61 <pre class="literallayout">std::iterator_traits&lt;Iter&gt;::difference_type</pre>
  62 <p>The difference type of the iterator</p>
  63 </li>
  64 <li class="listitem">
  65 <p><span class="bold"><strong>category</strong></span></p>
  66 <pre class="literallayout">std::iterator_traits&lt;Iter&gt;::iterator_category</pre>
  67 <p>The category of the iterator</p>
  68 </li>
  69 </ul></div>
  70 </div>
  71 <div class="refsect1">
  72 <a name="idp634283520"></a><h2>Notation</h2>
  73 <div class="variablelist"><dl class="variablelist">
  74 <dt><span class="term">Iter</span></dt>
  75 <dd>A type playing the role of iterator-type in the <a class="link" href="InputIterator.html" title="Concept InputIterator">InputIterator</a> concept.</dd>
  76 <dt>
  77 <span class="term"><code class="varname">i</code>, </span><span class="term"><code class="varname">j</code></span>
  78 </dt>
  79 <dd>Objects of type Iter</dd>
  80 <dt><span class="term"><code class="varname">x</code></span></dt>
  81 <dd>Object of type value_type</dd>
  82 </dl></div>
  83 </div>
  84 <div class="refsect1">
  85 <a name="idp634288016"></a><h2>Type expressions</h2>
  86 <div class="variablelist"><dl class="variablelist">
  87 <dt><span class="term">Category tag</span></dt>
  88 <dd><p><span class="type">category</span> must be
  89                   derived from <span class="type">std::input_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>.
  90                 </p></dd>
  91 <dt><span class="term">Value type copy constructibility</span></dt>
  92 <dd><p><span class="type">value_type</span> must be
  93                    a model  of <a class="link" href="CopyConstructible.html" title="Concept CopyConstructible">CopyConstructible</a>.
  94                 </p></dd>
  95 <dt><span class="term">Difference type properties</span></dt>
  96 <dd><p><span class="type">difference_type</span> must be
  97                    a model  of <a class="link" href="SignedInteger.html" title="Concept SignedInteger">SignedInteger</a>.
  98                 </p></dd>
  99 </dl></div>
 100 </div>
 101 <div class="refsect1">
 102 <a name="idp634295824"></a><h2>Valid expressions</h2>
 103 <div class="informaltable"><table class="table">
 104 <colgroup>
 105 <col>
 106 <col>
 107 <col>
 108 <col>
 109 <col>
 110 <col>
 111 </colgroup>
 112 <thead><tr>
 113 <th>Name</th>
 114 <th>Expression</th>
 115 <th>Type</th>
 116 <th>Precondition</th>
 117 <th>Semantics</th>
 118 <th>Postcondition</th>
 119 </tr></thead>
 120 <tbody>
 121 <tr>
 122 <td><p>Dereference</p></td>
 123 <td><p>*i</p></td>
 124 <td><p>Convertible to <span class="type">value_type</span></p></td>
 125 <td><p><code class="computeroutput">i</code> is incrementable (not
 126     off-the-end)</p></td>
 127 <td>&#160;</td>
 128 <td>&#160;</td>
 129 </tr>
 130 <tr>
 131 <td><p>Preincrement</p></td>
 132 <td><p>++i</p></td>
 133 <td><p><span class="type">Iter &amp;</span></p></td>
 134 <td><p><code class="computeroutput">i</code> is incrementable (not
 135     off-the-end)</p></td>
 136 <td>&#160;</td>
 137 <td>&#160;</td>
 138 </tr>
 139 <tr>
 140 <td><p>Postincrement</p></td>
 141 <td><p>i++</p></td>
 142 <td><p></p></td>
 143 <td><p><code class="computeroutput">i</code> is incrementable (not
 144     off-the-end)</p></td>
 145 <td><p>Equivalent to <code class="computeroutput">(void)(++i)</code></p></td>
 146 <td><p><code class="computeroutput">i</code> is dereferenceable or
 147     off-the-end</p></td>
 148 </tr>
 149 <tr>
 150 <td><p>Postincrement and dereference</p></td>
 151 <td><p>*i++</p></td>
 152 <td><p>Convertible to <span class="type">value_type</span></p></td>
 153 <td><p><code class="computeroutput">i</code> is incrementable (not
 154     off-the-end)</p></td>
 155 <td><p>Equivalent to <code class="computeroutput">{value_type t = *i; ++i; return t;}</code></p></td>
 156 <td><p><code class="computeroutput">i</code> is dereferenceable or
 157     off-the-end</p></td>
 158 </tr>
 159 </tbody>
 160 </table></div>
 161 </div>
 162 <div class="refsect1">
 163 <a name="idp634313152"></a><h2>Complexity</h2>
 164 <p>
 165   All iterator operations must take amortized constant time.
 166   </p>
 167 </div>
 168 <div class="refsect1">
 169 <a name="idp634313904"></a><h2>Models</h2>
 170 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="simplelist"><span class="type">std::istream_iterator</span></span></li></ul></div>
 171 </div>
 172 <div class="refsect1">
 173 <a name="idp634315392"></a><h2>See also</h2>
 174 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
 175 <li class="listitem"><p><a class="link" href="DefaultConstructible.html" title="Concept DefaultConstructible">DefaultConstructible</a></p></li>
 176 <li class="listitem"><p><a class="link" href="EqualityComparable.html" title="Concept EqualityComparable">EqualityComparable</a></p></li>
 177 </ul></div>
 178 </div>
 179 </div>
 180 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 181 <td align="left"></td>
 182 <td align="right"><div class="copyright-footer">Copyright &#169; 2001, 2002 Indiana University<br>Copyright &#169; 2000, 2001 University of Notre Dame du Lac<br>Copyright &#169; 2000 Jeremy Siek, Lie-Quan Lee, Andrew Lumsdaine<br>Copyright &#169; 1996-1999 Silicon Graphics Computer Systems, Inc.<br>Copyright &#169; 1994 Hewlett-Packard Company<p>Distributed under the Boost Software License, Version 1.0.
 183       (See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at
 184       <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
 185       </p>
 186 <p>This product includes software developed at the University
 187       of Notre Dame and the Pervasive Technology Labs at Indiana
 188       University. For technical information contact Andrew Lumsdaine
 189       at the Pervasive Technology Labs at Indiana University.  For
 190       administrative and license questions contact the Advanced
 191       Research and Technology Institute at 351 West 10th Street.
 192       Indianapolis, Indiana 46202, phone 317-278-4100, fax
 193       317-274-5902.</p>
 194 <p>Some concepts based on versions from the MTL draft manual
 195       and Boost Graph and Property Map documentation, the SGI Standard
 196       Template Library documentation and the Hewlett-Packard STL,
 197       under the following license:
 198         </p>
 199 <div class="blockquote"><blockquote class="blockquote"><p>Permission to use, copy, modify, distribute and
 200         sell this software and its documentation for any purpose is
 201         hereby granted without fee, provided that the above copyright
 202         notice appears in all copies and that both that copyright
 203         notice and this permission notice appear in supporting
 204         documentation.  Silicon Graphics makes no representations
 205         about the suitability of this software for any purpose.  It is
 206         provided "as is" without express or implied
 207         warranty.</p></blockquote></div>
 208 </div></td>
 209 </tr></table>
 210 <hr>
 211 <div class="spirit-nav">
 212 <a accesskey="p" href="Assignable.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="idp14900640-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="OutputIterator.html"><img src="../../doc/src/images/next.png" alt="Next"></a>
 213 </div>
 214 </body>
 215 </html>