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<div class="titlepage"><div><div><h3 class="title">
<a name="phoenix.modules.statement"></a><a class="link" href="statement.html" title="Statement">Statement</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="statement/block_statement.html">Block Statement</a></span></dt>
<dt><span class="section"><a href="statement/if__statement.html">if_ Statement</a></span></dt>
<dt><span class="section"><a href="statement/___if_else_____statement.html">if_else_ Statement</a></span></dt>
<dt><span class="section"><a href="statement/switch__statement.html">switch_
Statement</a></span></dt>
<dt><span class="section"><a href="statement/while__statement.html">while_
Statement</a></span></dt>
<dt><span class="section"><a href="statement/___do_while_____statement.html">do_while_ Statement</a></span></dt>
<dt><span class="section"><a href="statement/for_statement.html">for_ Statement</a></span></dt>
<dt><span class="section"><a href="statement/try__catch__statement.html">try_
catch_ Statement</a></span></dt>
<dt><span class="section"><a href="statement/throw_.html">throw_</a></span></dt>
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<p>
<span class="bold"><strong><span class="emphasis"><em>Lazy statements...</em></span></strong></span>
</p>
<p>
The expressions presented so far are sufficiently powerful to construct quite
elaborate structures. We have presented lazy-functions and lazy-operators.
How about lazy-statements? First, an appetizer:
</p>
<p>
Print all odd-numbered contents of an STL container using <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">for_each</span></code>
(<a href="../../../../example/all_odds.cpp" target="_top">all_odds.cpp</a>):
</p>
<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>
<span class="identifier">if_</span><span class="special">(</span><span class="identifier">arg1</span> <span class="special">%</span> <span class="number">2</span> <span class="special">==</span> <span class="number">1</span><span class="special">)</span>
<span class="special">[</span>
<span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">arg1</span> <span class="special"><<</span> <span class="char">' '</span>
<span class="special">]</span>
<span class="special">);</span>
</pre>
<p>
Huh? Is that valid C++? Read on...
</p>
<p>
Yes, it is valid C++. The sample code above is as close as you can get to
the syntax of C++. This stylized C++ syntax differs from actual C++ code.
First, the <code class="computeroutput"><span class="keyword">if</span></code> has a trailing
underscore. Second, the block uses square brackets instead of the familiar
curly braces {}.
</p>
<div class="note"><table border="0" summary="Note">
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<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top">
<p>
<span class="bold"><strong>C++ in C++?</strong></span>
</p>
<p>
In as much as <a href="http://spirit.sourceforge.net" target="_top">Spirit</a>
attempts to mimic EBNF in C++, Phoenix attempts to mimic C++ in C++!!!
</p>
</td></tr>
</table></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
Unlike lazy functions and lazy operators, lazy statements always return
void.
</p></td></tr>
</table></div>
<p>
Here are more examples with annotations. The code almost speaks for itself.
</p>
</div>
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<td align="right"><div class="copyright-footer">Copyright © 2002-2005, 2010, 2014 Joel de Guzman, Dan Marsden, Thomas Heller, John
Fletcher<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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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