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  27 <a name="phoenix.modules.statement.___if_else_____statement"></a><a class="link" href="___if_else_____statement.html" title="if_else_ Statement">if_else_ Statement</a>
  28 </h4></div></div></div>
  29 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">phoenix</span><span class="special">/</span><span class="identifier">statement</span><span class="special">/</span><span class="keyword">if</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
  30 </pre>
  31 <p>
  32           The syntax is
  33         </p>
  34 <pre class="programlisting"><span class="identifier">if_</span><span class="special">(</span><span class="identifier">conditional_expression</span><span class="special">)</span>
  35 <span class="special">[</span>
  36     <span class="identifier">sequenced_statements</span>
  37 <span class="special">]</span>
  38 <span class="special">.</span><span class="identifier">else_</span>
  39 <span class="special">[</span>
  40     <span class="identifier">sequenced_statements</span>
  41 <span class="special">]</span>
  42 </pre>
  43 <p>
  44           Take note that <code class="computeroutput"><span class="keyword">else</span></code> has a
  45           leading dot and a trailing underscore: <code class="computeroutput"><span class="special">.</span><span class="identifier">else_</span></code>
  46         </p>
  47 <p>
  48           Example: This code prints out all the elements and appends <code class="computeroutput"><span class="string">" &gt; 5"</span></code>, <code class="computeroutput"><span class="string">"
  49           == 5"</span></code> or <code class="computeroutput"><span class="string">" &lt; 5"</span></code>
  50           depending on the element's actual value:
  51         </p>
  52 <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">for_each</span><span class="special">(</span><span class="identifier">c</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">c</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span>
  53     <span class="identifier">if_</span><span class="special">(</span><span class="identifier">arg1</span> <span class="special">&gt;</span> <span class="number">5</span><span class="special">)</span>
  54     <span class="special">[</span>
  55         <span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">arg1</span> <span class="special">&lt;&lt;</span> <span class="string">" &gt; 5\n"</span>
  56     <span class="special">]</span>
  57     <span class="special">.</span><span class="identifier">else_</span>
  58     <span class="special">[</span>
  59         <span class="identifier">if_</span><span class="special">(</span><span class="identifier">arg1</span> <span class="special">==</span> <span class="number">5</span><span class="special">)</span>
  60         <span class="special">[</span>
  61             <span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">arg1</span> <span class="special">&lt;&lt;</span> <span class="string">" == 5\n"</span>
  62         <span class="special">]</span>
  63         <span class="special">.</span><span class="identifier">else_</span>
  64         <span class="special">[</span>
  65             <span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">arg1</span> <span class="special">&lt;&lt;</span> <span class="string">" &lt; 5\n"</span>
  66         <span class="special">]</span>
  67     <span class="special">]</span>
  68 <span class="special">);</span>
  69 </pre>
  70 <p>
  71           Notice how the <code class="computeroutput"><span class="identifier">if_else_</span></code>
  72           statement is nested.
  73         </p>
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  77 <td align="right"><div class="copyright-footer">Copyright &#169; 2002-2005, 2010, 2014, 2015 Joel de Guzman, Dan Marsden, Thomas
  78       Heller, John Fletcher<p>
  79         Distributed under the Boost Software License, Version 1.0. (See accompanying
  80         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>)
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