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: distance</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="./advance.html" class="navigation-link">Prev</a> <a href="./next.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./advance.html" class="navigation-link">Back</a> <a href="./next.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iterator-metafunctions.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="./iterator-metafunctions.html" class="navigation-link">Iterator Metafunctions</a> / <a href="./distance.html" class="navigation-link">distance</a></td> 13</tr></table><div class="header-separator"></div> 14<div class="section" id="distance"> 15<h1><a class="toc-backref" href="./iterator-metafunctions.html#id1455">distance</a></h1> 16<div class="section" id="id412"> 17<h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> 18<pre class="literal-block"> 19template< 20 typename First 21 , typename Last 22 > 23struct <a href="./distance.html" class="identifier">distance</a> 24{ 25 typedef <em>unspecified</em> type; 26}; 27</pre> 28</div> 29<div class="section" id="id413"> 30<h3><a class="subsection-title" href="#description" name="description">Description</a></h3> 31<p>Returns the distance between <tt class="literal"><span class="pre">First</span></tt> and <tt class="literal"><span class="pre">Last</span></tt> iterators, that is, an 32<a class="reference internal" href="./integral-constant.html">Integral Constant</a> <tt class="literal"><span class="pre">n</span></tt> such that <tt class="literal"><span class="pre"><a href="./advance.html" class="identifier">advance</a><First,n>::type</span></tt> is 33identical to <tt class="literal"><span class="pre">Last</span></tt>.</p> 34</div> 35<div class="section" id="id414"> 36<h3><a class="subsection-title" href="#header" name="header">Header</a></h3> 37<pre class="literal-block"> 38#include <<a href="../../../../boost/mpl/distance.hpp" class="header">boost/mpl/distance.hpp</a>> 39</pre> 40</div> 41<div class="section" id="id415"> 42<h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> 43<table border="1" class="docutils table"> 44<colgroup> 45<col width="19%" /> 46<col width="35%" /> 47<col width="45%" /> 48</colgroup> 49<thead valign="bottom"> 50<tr><th class="head">Parameter</th> 51<th class="head">Requirement</th> 52<th class="head">Description</th> 53</tr> 54</thead> 55<tbody valign="top"> 56<tr><td><tt class="literal"><span class="pre">First</span></tt>, 57<tt class="literal"><span class="pre">Last</span></tt></td> 58<td><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a></td> 59<td>Iterators to compute a 60distance between.</td> 61</tr> 62</tbody> 63</table> 64</div> 65<div class="section" id="id416"> 66<h3><a class="subsection-title" href="#model-of" name="model-of">Model Of</a></h3> 67<p><a class="reference internal" href="./tag-dispatched-metafunction.html">Tag Dispatched Metafunction</a></p> 68</div> 69<div class="section" id="id417"> 70<h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> 71<p>For any <a class="reference internal" href="./forward-iterator.html">Forward Iterator</a>s <tt class="literal"><span class="pre">first</span></tt> and <tt class="literal"><span class="pre">last</span></tt>:</p> 72<pre class="literal-block"> 73typedef <a href="./distance.html" class="identifier">distance</a><first,last>::type n; 74</pre> 75<table class="docutils field-list" frame="void" rules="none"> 76<col class="field-name" /> 77<col class="field-body" /> 78<tbody valign="top"> 79<tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./integral-constant.html">Integral Constant</a>.</p> 80</td> 81</tr> 82<tr class="field"><th class="field-name">Precondition:</th><td class="field-body"><p class="first">[<tt class="literal"><span class="pre">first</span></tt>, <tt class="literal"><span class="pre">last</span></tt>) is a valid range.</p> 83</td> 84</tr> 85<tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> 86<pre class="literal-block"> 87typedef <a href="./iter-fold.html" class="identifier">iter_fold</a>< 88 <a href="./iterator-range.html" class="identifier">iterator_range</a><first,last> 89 , <a href="./long.html" class="identifier">long_</a><0> 90 , <a href="./next.html" class="identifier">next</a><<a href="./placeholders.html" class="identifier">_1</a>> 91 >::type n; 92</pre> 93</td> 94</tr> 95<tr class="field"><th class="field-name">Postcondition:</th><td class="field-body"><p class="first last"><tt class="literal"><span class="pre">is_same<</span> <span class="pre"><a href="./advance.html" class="identifier">advance</a><first,n>::type,</span> <span class="pre">last</span> <span class="pre">>::value</span> <span class="pre">==</span> <span class="pre">true</span></tt>.</p> 96</td> 97</tr> 98</tbody> 99</table> 100</div> 101<div class="section" id="id418"> 102<h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> 103<p>Amortized constant time if <tt class="literal"><span class="pre">first</span></tt> and <tt class="literal"><span class="pre">last</span></tt> are <a class="reference internal" href="./random-access-iterator.html">Random Access Iterator</a>s, 104otherwise linear time.</p> 105</div> 106<div class="section" id="id419"> 107<h3><a class="subsection-title" href="#example" name="example">Example</a></h3> 108<pre class="literal-block"> 109typedef <a href="./range-c.html" class="identifier">range_c</a><int,0,10>::type range; 110typedef <a href="./begin.html" class="identifier">begin</a><range>::type first; 111typedef <a href="./end.html" class="identifier">end</a><range>::type last; 112 113<a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./distance.html" class="identifier">distance</a><first,last>::value), ==, 10); 114</pre> 115</div> 116<div class="section" id="id420"> 117<h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> 118<p><a class="reference internal" href="./iterators.html">Iterators</a>, <a class="reference internal" href="./tag-dispatched-metafunction.html">Tag Dispatched Metafunction</a>, <a class="reference internal" href="./advance.html">advance</a>, <a class="reference internal" href="./next.html">next</a>, <a class="reference internal" href="./prior.html">prior</a></p> 119<!-- Iterators/Iterator Metafunctions//next |30 --> 120</div> 121</div> 122 123<div class="footer-separator"></div> 124<table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./advance.html" class="navigation-link">Prev</a> <a href="./next.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./advance.html" class="navigation-link">Back</a> <a href="./next.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./iterator-metafunctions.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> 125<td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> 126Distributed under the Boost Software License, Version 1.0. (See accompanying 127file 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> 128</html> 129