<?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> <title>The MPL Reference Manual: distance</title> <link rel="stylesheet" href="../style.css" type="text/css" /> </head> <body class="docframe refmanual"> <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> <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> </tr></table><div class="header-separator"></div> <div class="section" id="distance"> <h1><a class="toc-backref" href="./iterator-metafunctions.html#id1455">distance</a></h1> <div class="section" id="id412"> <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> <pre class="literal-block"> template< typename First , typename Last > struct <a href="./distance.html" class="identifier">distance</a> { typedef <em>unspecified</em> type; }; </pre> </div> <div class="section" id="id413"> <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> <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 <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 identical to <tt class="literal"><span class="pre">Last</span></tt>.</p> </div> <div class="section" id="id414"> <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> <pre class="literal-block"> #include <<a href="../../../../boost/mpl/distance.hpp" class="header">boost/mpl/distance.hpp</a>> </pre> </div> <div class="section" id="id415"> <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> <table border="1" class="docutils table"> <colgroup> <col width="19%" /> <col width="35%" /> <col width="45%" /> </colgroup> <thead valign="bottom"> <tr><th class="head">Parameter</th> <th class="head">Requirement</th> <th class="head">Description</th> </tr> </thead> <tbody valign="top"> <tr><td><tt class="literal"><span class="pre">First</span></tt>, <tt class="literal"><span class="pre">Last</span></tt></td> <td><a class="reference internal" href="./forward-iterator.html">Forward Iterator</a></td> <td>Iterators to compute a distance between.</td> </tr> </tbody> </table> </div> <div class="section" id="id416"> <h3><a class="subsection-title" href="#model-of" name="model-of">Model Of</a></h3> <p><a class="reference internal" href="./tag-dispatched-metafunction.html">Tag Dispatched Metafunction</a></p> </div> <div class="section" id="id417"> <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> <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> <pre class="literal-block"> typedef <a href="./distance.html" class="identifier">distance</a><first,last>::type n; </pre> <table class="docutils field-list" frame="void" rules="none"> <col class="field-name" /> <col class="field-body" /> <tbody valign="top"> <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> </td> </tr> <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> </td> </tr> <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p> <pre class="literal-block"> typedef <a href="./iter-fold.html" class="identifier">iter_fold</a>< <a href="./iterator-range.html" class="identifier">iterator_range</a><first,last> , <a href="./long.html" class="identifier">long_</a><0> , <a href="./next.html" class="identifier">next</a><<a href="./placeholders.html" class="identifier">_1</a>> >::type n; </pre> </td> </tr> <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> </td> </tr> </tbody> </table> </div> <div class="section" id="id418"> <h3><a class="subsection-title" href="#complexity" name="complexity">Complexity</a></h3> <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, otherwise linear time.</p> </div> <div class="section" id="id419"> <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> <pre class="literal-block"> typedef <a href="./range-c.html" class="identifier">range_c</a><int,0,10>::type range; typedef <a href="./begin.html" class="identifier">begin</a><range>::type first; typedef <a href="./end.html" class="identifier">end</a><range>::type last; <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( (<a href="./distance.html" class="identifier">distance</a><first,last>::value), ==, 10); </pre> </div> <div class="section" id="id420"> <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> <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> <!-- Iterators/Iterator Metafunctions//next |30 --> </div> </div> <div class="footer-separator"></div> <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> <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> Distributed under the Boost Software License, Version 1.0. (See accompanying file 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> </html>