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>polymorphic_downcast example</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="../conversion.html" title="Chapter 11. The Conversion Library 1.6"> 10<link rel="prev" href="_polymorphic_cast____polymorphic_downcast____polymorphic_pointer_cast__and__polymorphic_pointer_downcast__synopsis.html" title="polymorphic_cast, polymorphic_downcast, polymorphic_pointer_cast and polymorphic_pointer_downcast synopsis"> 11<link rel="next" href="_polymorphic_pointer_downcast__example.html" title="polymorphic_pointer_downcast example"> 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="_polymorphic_cast____polymorphic_downcast____polymorphic_pointer_cast__and__polymorphic_pointer_downcast__synopsis.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../conversion.html"><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="_polymorphic_pointer_downcast__example.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> 25</div> 26<div class="section"> 27<div class="titlepage"><div><div><h2 class="title" style="clear: both"> 28<a name="conversion._polymorphic_downcast__example"></a><a class="link" href="_polymorphic_downcast__example.html" title="polymorphic_downcast example"><code class="computeroutput">polymorphic_downcast</code> 29 example</a> 30</h2></div></div></div> 31<pre class="programlisting">#include <boost/polymorphic_cast.hpp> 32... 33class Fruit { public: virtual ~Fruit(){}; ... }; 34class Banana : public Fruit { ... }; 35... 36void f( Fruit * fruit ) { 37 // ... logic which leads us to believe it is a Banana 38 Banana * banana = boost::polymorphic_downcast<Banana*>(fruit); 39 ... 40} 41</pre> 42</div> 43<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 44<td align="left"></td> 45<td align="right"><div class="copyright-footer">Copyright © 2001 Beman Dawes<br>Copyright © 2014-2019 Antony Polukhin<p> 46 Distributed under the Boost Software License, Version 1.0. (See accompanying 47 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 48 </p> 49</div></td> 50</tr></table> 51<hr> 52<div class="spirit-nav"> 53<a accesskey="p" href="_polymorphic_cast____polymorphic_downcast____polymorphic_pointer_cast__and__polymorphic_pointer_downcast__synopsis.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../conversion.html"><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="_polymorphic_pointer_downcast__example.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> 54</div> 55</body> 56</html> 57
