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 Sequence</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-sequence.html" class="navigation-link">Prev</a> <a href="./extensible-sequence.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./bidirectional-sequence.html" class="navigation-link">Back</a> <a href="./extensible-sequence.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./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="./sequences.html" class="navigation-link">Sequences</a> / <a href="./concepts.html" class="navigation-link">Concepts</a> / <a href="./random-access-sequence.html" class="navigation-link">Random Access Sequence</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="random-access-sequence"> 15<h1><a class="toc-backref" href="./concepts.html#id1397">Random Access Sequence</a></h1> 16<div class="section" id="id6"> 17<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 18<p>A <a class="reference internal" href="./random-access-sequence.html">Random Access Sequence</a> is a <a class="reference internal" href="./bidirectional-sequence.html">Bidirectional Sequence</a> whose iterators model 19<a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a>. A random access sequence guarantees amortized constant 20time access to an arbitrary sequence element.</p> 21</div> 22<div class="section" id="id7"> 23<h3><a class="subsection-title" href="#refinement-of" name="refinement-of">Refinement of</a></h3> 24<p><a class="reference internal" href="./bidirectional-sequence.html">Bidirectional Sequence</a></p> 25</div> 26<div class="section" id="id8"> 27<h3><a class="subsection-title" href="#expression-requirements" name="expression-requirements">Expression requirements</a></h3> 28<p>In addition to the requirements defined in <a class="reference internal" href="./bidirectional-sequence.html">Bidirectional Sequence</a>, 29for any <a class="reference internal" href="./random-access-sequence.html">Random Access Sequence</a> <tt class="literal"><span class="pre">s</span></tt> the following must be met:</p> 30<table border="1" class="docutils table"> 31<colgroup> 32<col width="30%" /> 33<col width="39%" /> 34<col width="30%" /> 35</colgroup> 36<thead valign="bottom"> 37<tr><th class="head">Expression</th> 38<th class="head">Type</th> 39<th class="head">Complexity</th> 40</tr> 41</thead> 42<tbody valign="top"> 43<tr><td><tt class="literal"><span class="pre"><a href="./begin.html" class="identifier">begin</a><s>::type</span></tt></td> 44<td><a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a></td> 45<td>Amortized constant time</td> 46</tr> 47<tr><td><tt class="literal"><span class="pre"><a href="./end.html" class="identifier">end</a><s>::type</span></tt></td> 48<td><a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a></td> 49<td>Amortized constant time</td> 50</tr> 51<tr><td><tt class="literal"><span class="pre"><a href="./at.html" class="identifier">at</a><s,n>::type</span></tt></td> 52<td>Any type</td> 53<td>Amortized constant time</td> 54</tr> 55</tbody> 56</table> 57</div> 58<div class="section" id="id9"> 59<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> 60<p>Semantics of an expression is defined only where it differs from, or is not 61defined in <a class="reference internal" href="./bidirectional-sequence.html">Bidirectional Sequence</a>.</p> 62<table border="1" class="docutils table"> 63<colgroup> 64<col width="28%" /> 65<col width="72%" /> 66</colgroup> 67<thead valign="bottom"> 68<tr><th class="head">Expression</th> 69<th class="head">Semantics</th> 70</tr> 71</thead> 72<tbody valign="top"> 73<tr><td><tt class="literal"><span class="pre"><a href="./at.html" class="identifier">at</a><s,n>::type</span></tt></td> 74<td>The <tt class="literal"><span class="pre">n</span></tt>th element from the beginning of the sequence; see <a class="reference internal" href="./at.html">at</a>.</td> 75</tr> 76</tbody> 77</table> 78</div> 79<div class="section" id="id10"> 80<h3><a class="subsection-title" href="#models" name="models">Models</a></h3> 81<ul class="simple"> 82<li><a class="reference internal" href="./vector.html">vector</a></li> 83<li><a class="reference internal" href="./range-c.html">range_c</a></li> 84</ul> 85</div> 86<div class="section" id="id11"> 87<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 88<p><a class="reference internal" href="./sequences.html">Sequences</a>, <a class="reference internal" href="./bidirectional-sequence.html">Bidirectional Sequence</a>, <a class="reference internal" href="./extensible-sequence.html">Extensible Sequence</a>, <a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a>, 89<a class="reference internal" href="./begin.html">begin</a> / <a class="reference internal" href="./end.html">end</a>, <a class="reference internal" href="./at.html">at</a></p> 90<!-- Sequences/Concepts//Extensible Sequence |40 --> 91</div> 92</div> 93 94<div class="footer-separator"></div> 95<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./bidirectional-sequence.html" class="navigation-link">Prev</a> <a href="./extensible-sequence.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./bidirectional-sequence.html" class="navigation-link">Back</a> <a href="./extensible-sequence.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./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> 96<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 97Distributed under the Boost Software License, Version 1.0. (See accompanying 98file 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> 99</html> 100