1<?xml version="1.0" encoding="utf-8" ?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> 4<head> 5<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 6<meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> 7<title>The MPL Reference Manual: Random Access Iterator</title> 8<link rel="stylesheet" href="../style.css" type="text/css" /> 9</head> 10<body class="docframe refmanual"> 11<table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./bidirectional-iterator.html" class="navigation-link">Prev</a> <a href="./iterator-metafunctions.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./bidirectional-iterator.html" class="navigation-link">Back</a> Along</span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iterators-concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 12<td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./iterators.html" class="navigation-link">Iterators</a> / <a href="./iterators-concepts.html" class="navigation-link">Concepts</a> / <a href="./random-access-iterator.html" class="navigation-link">Random Access Iterator</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="random-access-iterator"> 15<h1><a class="toc-backref" href="./iterators-concepts.html#id1452">Random Access Iterator</a></h1> 16<div class="section" id="id397"> 17<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 18<p>A <a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a> is a <a class="reference internal" href="./bidirectional-iterator.html">Bidirectional Iterator</a> that provides 19constant-time guarantees on moving the iterator an arbitrary number of positions 20forward or backward and for measuring the distance to another iterator in the 21same sequence.</p> 22</div> 23<div class="section" id="id398"> 24<h3><a class="subsection-title" href="#refinement-of" name="refinement-of">Refinement of</a></h3> 25<p><a class="reference internal" href="./bidirectional-iterator.html">Bidirectional Iterator</a></p> 26</div> 27<div class="section" id="id399"> 28<h3><a class="subsection-title" href="#expression-requirements" name="expression-requirements">Expression requirements</a></h3> 29<p>In addition to the requirements defined in <a class="reference internal" href="./bidirectional-iterator.html">Bidirectional Iterator</a>, 30the following requirements must be met.</p> 31<table border="1" class="docutils table"> 32<colgroup> 33<col width="28%" /> 34<col width="44%" /> 35<col width="28%" /> 36</colgroup> 37<thead valign="bottom"> 38<tr><th class="head">Expression</th> 39<th class="head">Type</th> 40<th class="head">Complexity</th> 41</tr> 42</thead> 43<tbody valign="top"> 44<tr><td><tt class="literal"><span class="pre"><a href="./next.html" class="identifier">next</a><i>::type</span></tt></td> 45<td><a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a></td> 46<td>Amortized constant time</td> 47</tr> 48<tr><td><tt class="literal"><span class="pre"><a href="./prior.html" class="identifier">prior</a><i>::type</span></tt></td> 49<td><a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a></td> 50<td>Amortized constant time</td> 51</tr> 52<tr><td><tt class="literal"><span class="pre">i::category</span></tt></td> 53<td><a class="reference internal" href="./integral-constant.html">Integral Constant</a>, convertible 54to <tt class="literal"><span class="pre">random_access_iterator_tag</span></tt></td> 55<td>Constant time</td> 56</tr> 57<tr><td><tt class="literal"><span class="pre"><a href="./advance.html" class="identifier">advance</a><i,n>::type</span></tt></td> 58<td><a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a></td> 59<td>Amortized constant time</td> 60</tr> 61<tr><td><tt class="literal"><span class="pre"><a href="./distance.html" class="identifier">distance</a><i,j>::type</span></tt></td> 62<td><a class="reference internal" href="./integral-constant.html">Integral Constant</a></td> 63<td>Amortized constant time</td> 64</tr> 65</tbody> 66</table> 67</div> 68<div class="section" id="id400"> 69<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> 70<pre class="literal-block"> 71typedef <a href="./advance.html" class="identifier">advance</a><i,n>::type j; 72</pre> 73<table class="docutils field-list" frame="void" rules="none"> 74<col class="field-name" /> 75<col class="field-body" /> 76<tbody valign="top"> 77<tr class="field"><th class="field-name">Semantics:</th><td class="field-body">See <tt class="literal"><span class="pre"><a href="./advance.html" class="identifier">advance</a></span></tt> specification</td> 78</tr> 79</tbody> 80</table> 81<!-- .......................................................................... --> 82<pre class="literal-block"> 83typedef <a href="./distance.html" class="identifier">distance</a><i,j>::type n; 84</pre> 85<table class="docutils field-list" frame="void" rules="none"> 86<col class="field-name" /> 87<col class="field-body" /> 88<tbody valign="top"> 89<tr class="field"><th class="field-name">Semantics:</th><td class="field-body">See <tt class="literal"><span class="pre"><a href="./distance.html" class="identifier">distance</a></span></tt> specification</td> 90</tr> 91</tbody> 92</table> 93</div> 94<div class="section" id="id401"> 95<h3><a class="subsection-title" href="#invariants" name="invariants">Invariants</a></h3> 96<p>For any random access iterators <tt class="literal"><span class="pre">i</span></tt> and <tt class="literal"><span class="pre">j</span></tt> the following invariants always 97hold:</p> 98<ul class="simple"> 99<li>If <tt class="literal"><span class="pre"><a href="./advance.html" class="identifier">advance</a><i,n>::type</span></tt> is well-defined, then 100<tt class="literal"><span class="pre"><a href="./advance.html" class="identifier">advance</a><</span> <span class="pre"><a href="./advance.html" class="identifier">advance</a><i,n>::type,</span> <span class="pre"><a href="./negate.html" class="identifier">negate</a><n>::type</span> <span class="pre">>::type</span></tt> is a null operation.</li> 101</ul> 102</div> 103<div class="section" id="id402"> 104<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 105<p><a class="reference internal" href="./iterators.html">Iterators</a>, <a class="reference internal" href="./bidirectional-iterator.html">Bidirectional Iterator</a>, <a class="reference internal" href="./random-access-sequence.html">Random Access Sequence</a>, <a class="reference internal" href="./advance.html">advance</a>, <a class="reference internal" href="./distance.html">distance</a></p> 106</div> 107</div> 108 109<div class="footer-separator"></div> 110<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./bidirectional-iterator.html" class="navigation-link">Prev</a> <a href="./iterator-metafunctions.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./bidirectional-iterator.html" class="navigation-link">Back</a> Along</span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iterators-concepts.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> 111<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 112Distributed under the Boost Software License, Version 1.0. (See accompanying 113file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body> 114</html> 115